Your question assumes that he could bring his whole diocese with him into the RCC; this betrays a lack of familiarity with the horrible state of disunity in the Episcopal Church in America.

Since the ’70s at least, TEC has touted itself as a “big tent” church, with High and Broad/Low traditions encompassed within it. From the late ’70s onward, however, the liberal factions have taken over the leadership and forced traditionalist congregations to accept their modern innovations, including women priests/bishops and changes in the liturgy, and now (since 2003) practicing homosexual priests and bishops.

Many offshoot branches of the Anglican church now exist in the US. You’ll often find several (traditionalist) congregations in a diocese which have repudiated their affiliation with their (revisionist) bishop. Some remain independent, yet retain the Anglican name; some are affiliated with African bishops overseas. So, the local bishop remains something of a figurehead, a symbol - but he has no power to comand anyone to follow him in anything, practically speaking.

The worldwide Anglican Communion is in crisis even as we speak, with the Archbishop of Canterbury having met this week with American bishops in New Orleans trying to stop them from ordaining gay people and blessing same-sex couples, which angers the much more numerous and influential bishops of the Global South, who are much more orthodox. A historic ecclesial shipwreck of Titanic proportions is likely to occur in the next six months or so.

I for one don’t blame Mr. Steenson in the least for wanting to swim the Tiber to shore.

If the good Bishop sincerely believes what the Church teaches, would he not seek to bring his entire diocese into Communion with Rome?