ATT had to pay T-Mobile when their deal fell through due to the government. Look at this way Twitter just made a whole bunch of business decisions based somewhat/mostly on Musk's takeover. If he pulls out, Twitter will be hurt financially. Or suppose it was a hostile takeover by a competitor - they could fein a takeover - hurt their competitor - then walk away.

I don't think he did. Section 8.3 deals with the termination fee and it doesn't list 8.1(b)(i) as a reason it gets paid. 8.1(b)(i) is the government blocking.