I don’t understand. Why would a stolen plane be most likely if you think another plane attack would never be undertaken?
BTW, I have long thought airplanes would not be used again. They are not that dumb. Well, at least not in the US or thereabouts. They weren’t dumb with the 9/11 targets - things that might disrupt our whole society, not just “symbols” as people so foolishly repeat over and over again.
A “stolen” plane would be the least expensive explanation for all concerned parties.
Any other conclusion would require a lot of questions to answer and a ton of lawsuits.