The “Biden stays” scenario is profoundly unwise because the idea that Biden “had a bad night” is delusional. Obama showed it’s possible to get wrong-footed at a debate and recover. Biden is largely incapable of clear extemporaneous speaking in general.
I gave up on Beutler a long time ago. He is a charter member of the "Joe Biden could run a marathon in 2 hours while juggling chainsaws and have the leader of every Middle East nation waiting at the finish line to sign a peace treaty among all of them and I'd still find something to criticize" club.