If he walks away he isnt going to pay it, Twitter will have to go to court to enforce it. Could take them years to see that money assuming they win..
Yes if Twitter willfully mislead regarding their fake accounts I doubt that $1b fee is going to be paid.
I doubt it’ll be paid too and the shareholders law suits too but this is a good example of be careful who you get into business with.
I believe Elon waived the right to due diligence as part of his offer. There’s almost no situation he doesn’t pay the breakup fee.
He did his DD before he made offer using public Twitter filings. So he will argue the contract was invalid if the filings and bot numbers are fake/fraudulent. But there will have to be big difference, a few percent more than 5% isn't going to cut it.