You are right, the thing is, these firms can always accept to be taken out at $420. All Musk needs to do is to convince them to vote for what he wants. The man was able to get rockets in space and land them back down, if he says 'this is the only way forward, otherwise this company might not be viable (or some other such exaggeration)' it will be hard for them to vote against. The Saudis easly have $20-$40B to cash out anyone that wants. This seems similar to Warren Buffett bringing a matter for a vote at BRK, its hard for him to lose a vote because the shareholder base is full of believers. He did get that $50B pay package approved this year afterall
But then he has to find an equity investor or a debt investor willing to take them out. My point is that it's not a 20bn transaction. It IS a 60bn transaction. Impossible to do with a company that's hemmoraging money in my opinion.