As razor_888 said, ToD mentions that after the Jihad, Peter was deposed by the Brotherhood of Cincinnatus because they felt he was tainted by his Davion blood. They installed Adam Steiner as Archon and he promptly turned around and hunted them down and destroyed them. What's that saying about being careful what you wish for? :p

ToD doesn't say exactly when this happened (except after the Jihad) but I think it was likely to have happened in 3084. That's the year the Lyran Alliance went back to being the Lyran Commonwealth, which seems like just the kind of action a group obsessed with "Steiner purity" might initiate. So I'm thinking they installed Adam on the throne and pressured him to change the name back. We'll have to wait and see to be sure, though.