As per your own link, the situations where that deal could be broken and the fee would be applicable were very limited (Musk not getting financing, Twitter finding a higher bidder). Musk changing his mind was not one of those situations, it was a binding deal.
Twitter did not sue for the $1b, but for specific perfomance, i.e. closing the deal.
Fair enough, I'm not versed on the legal in's and out's and it appears you're correct.
I knew Twitter sought to close the deal, but most of the analysis I read claimed they could have chosen the $1B instead, as if both were viable legal paths. It appears that is incorrect.
Twitter did not sue for the $1b, but for specific perfomance, i.e. closing the deal.