Based on other comments in this thread, your hypothesis (while interesting) might fall short. Apparently there is a legal stipulation that if bank financing falls through, Musk is personally on the hook to make up the difference.
If the stipulation is in place, Musk can't use the bank's failure to finance as a scapegoat for the deal falling through. He can't walk away from the deal paying a 1 billion dollar penalty, he will have to buy Twitter at the original agreed upon price.
That being said, if your hypothesis is valid and the deal falls apart due to lack of financing -- buying some put options on Twitter right now could prove to be an extremely profitable move.
Musk actually can get out of the deal if he doesn't have the financing. But he has the financing, because the banks signed commitment letters. These commitment letters are valid until the beginning of next year. That's why he tried to drag out the lawsuit in the hope, that deadline might be passed.
It’s not a happy day for the banks, and they may yet try to walk, but they will absolutely have legal exposure if they do. When Musk started getting second thoughts, Grimes (the Morgan Stanley Grimes, not the surrogate Grimes) started distancing himself from that aspect of this clown show right away.
But,
a) The banks may well be able to sell these bonds, just with a higher yield. b) Maybe there are some clients out there with lotsa cash (Buffet, Bezos, Gates) who would love to have Elon owe them tens of billions of dollars at 10% yield.
If the whole thing goes tits up, then the bondholders own Twitter, not Elon.