Theymos has done it before but he's away atm. Maybe Badbear can do it now though.
I doubt it. I think theymos mentioned has to directly edit the database to change the ownership of a thread which BadBear doesn't have access to, as far as I know.
A long time ago, I had to get theymos to change thread ownership, I was told he is the only one with DB access, This probably still is the case.