While there seems to be unanimity (including the strong implication of Steenson's own statements) that he abrogated his vows in leaving his post as a bishop in The Episcopal Church, I think the extensive timeline connected with the establishment of the US Ordinariate also calls into question the sincerity of his statements on why he left that denomination.
Steenson had apparently been in contact with Bernard Law, the US delegate for John Paul II's Pastoral Provision allowing married Episcopal priests to become Catholic priests, since at least the late 1980s. Cardinal Law has been a consistent figure throughout this story, in fact: he arranged the 1993 meeting of Bishop Pope, then-Fr Steenson, and Cardinal Ratzinger, and he appears to have been involved, with his close associate Msgr William Stetson, in all phases of the story through his reception of Steenson into the Catholic Church at the Basilica of St Mary Major, where Law served as archpriest, in Rome in 2007.
Like a good juror is expected to do, I have to bring my own experiences to bear in evaluating evidence. In the corporate world, nothing happens by accident at the senior vice president level. The subjects of meetings are agreed in advance. The outcomes of the meetings are foreordained as well; they are based on detailed proposals that have been carefully drafted by staff and thoroughly reviewed at lower levels before they're presented on mahogany row. If anything, I've got to assume that an institution like the Catholic Church operates like this even more than an American corporation.
Nobody just walks in on the Prefect of the Congregation for the Doctrine of the Faith -- I know things work that way, in the same way that the centurion with the paralyzed servant understood, based on his own experience in a different field, that if Our Lord gave an order, the order took. The 1993 meeting was set up by Cardinal Law, and we must assume that flights from Texas to Italy, hotel rooms, and the like, weren't booked just so everyone could shake hands. Cardinal Law had been talking to the Fort Worth crowd for years; he thought there was finally something they could say to Cardinal Ratzinger that wouldn't waste his time.
So I think it was deliberately misleading for Steenson to characterize the 1993 meeting to the 2008 Anglican Use Conference as simply exploratory. Formal sitdowns with senior vice presidents aren't exploratory, sorry. Steenson needed to mislead the Anglican Use Conference attendees, because the pattern of his conduct throughout his Episcopal Church career was, we can reasonably conclude, duplicitous.
I think this goes as well to the chronology of his final (and we may assume long-delayed) decision to leave the denomination. A House of Bishops meeting in March, 2007 was the last straw, in Steenson's account, although Steenson had presumably been ordained using a rite from the 1979 BCP into a denomination that already ordained women; he'd tolerated the ordination of Barbara Harris as a bishop in 1989; he'd been through the Jack Spong controversies in the 1990s, and he'd specifically said the ordination of Eugene Robinson as a partnered gay in 2003 wasn't a reason for leaving The Episcopal Church. But some minor thing in 2007 was positively the last straw!
By September 2007, the date of his letter to the Rio Grande clergy, he'd worked it all out with Presiding Bishop Jefferts Schori. In the same 2008 address, Steenson says, "My counselors, Monsignor William Stetson and Archbishop Michael Sheehan, urged me to bring my ministry in the Episcopal Church to a close as honorably as possible." Well, all I can say is that if I had a true last-straw moment, I'd be out the door in a huff, as I occasionally was in my secular career. Yet it seems to me that Steenson spent the time between March and September being careful -- in particular, I would guess, being extremely careful that he didn't invoke Episcopal disciplinary procedures, which would almost certainly destroy his chances of becoming US Ordinary. This would have been the real intent of Stetson's counsel in particular -- Stetson, Bernard Law's right arm, is a canon lawyer, after all.
The written record indicates that Bernard Law, after years of no contact with Bishop Clarence Pope, contacted him again in 2003, somewhat to Pope's surprise. However, Law appears to have dropped the contact immediately after that. My surmise would be that the 1993-4 proposal for a US Anglican personal prelature was coming back to life, for whatever reason, and Law was trying to determine Pope's level of health and overall interest if the project should move forward. In 2003, Pope would have been the only candidate for Ordinary, since he was the only former Episcopal bishop.
Steenson, however, by 2003 was Canon to the Ordinary at the Episcopal Diocese of the Rio Grande, a post that could easily lead to being named bishop, at Rio Grande or elsewhere. By 2004, he'd become Bishop Coadjutor of the Rio Grande, in line to become diocesan at his predecessor's retirement. In other words, he'd had his bishop ticket punched, while Pope, aged, in poor health, and unstable, was no longer a credible candidate.
My own view is that the Vatican had Steenson clearly lined up as the potential Ordinary at the time of his election as a bishop in 2004, and Steenson was aware of this. The likelihood of a US Ordinariate was assured when Ratzinger become Benedict XVI in 2005. The only small issue, when the time came to move, would be to find a pretext -- a last-straw moment -- for Steenson to leave, and then to wait a decent interval before erecting the Ordinariate and naming him Ordinary. As far as I can see, this is the only reasonable conclusion to be drawn from events -- I don't see nearly 25 years of coincidence here.
What does this say of this man's character? Careerist is probably a generous interpretation.