not a stretch at all, and the "chair" is not where he sits....a proclamation from the chair of Peter means that the pope is speaking ex cathedra....officially, not expressing an opinion. He could be standing, writing, whatever....when he issues a statement OFFICIALLY....FROM THE "CHAIR OF PETER" it cannot be in error.
Is there a list of infallible, ex cathedra statements made from the chair of Peter? It would be interesting reading.
You are mistaken...I find it interesting that other Catholics will not correct you on this so I guess I have to...
There IS a chair...A Catholic Throne that is designed for the purpose of the pope leading from and doing his ex-cathedra thing...
Your current pope had it removed but not so very long ago, he had the 'throne' put back in place...Presumably so the next winner can do his thing from that throne...