Plenty of room for Elon to re-trade on purchase price also. They haven't made it through due diligence and it's quite easy for buyers of companies to find things they don't like. The twitter share price also down, along with the rest of the market FWIW and if users are exiting the platform at higher rates, he would have room to renegotiate.
The country thinks this is about free speech but it's about really about advertising and market influence. I presented an idea to Google about 5 years ago around using their advertising framework as a stock locate capability. So think like when you and nytiger get a popup for a webstore to buy an AOC Tax the Rich t-shirt, the same model can be used for stock locate......ie, you get a popup from an asset manager/bank saying they have a 5,000 lot Apple position at x price....one click trade, etc etc which is all based on your search history. Google shot it down as they didn't want to be regulated and thought the usage of search history might be scrutinized (despite them already doing that) but they did like the idea.
I'm not suggesting Twitter turns into the above but social sentiment is a great indicator of market momentum. There are lots of great innovation ideas that can be built around that which have nothing to do with free speech.
Lastly, the breakup clauses in SPA's (purchase agreements) are usually quite granular as to what can constitute a breakup and what would trigger the $1b fee. It's not just capital at risk, it's reputation as well. He will be under pressure from those servicing the debt as well as his banker structuring the deal. M&A costs tons of money......the risk on a lower tesla stock price has already been factored into this, well before the offer was made.