Even without following the letter of the law it's entirely rational behaviour for a popular market leader to foment outrage by fully blacking out services. 150 million users (in the US alone) is a very powerful political influence. Politicians frequently fold for a few thousand vocal people complaining on the internet.
Of course it's rational behavior. Nico was the one claiming that they were just "following the law", that's what this subthread was about. If you agree that TikTok was making a political point by shutting down, then you agree with the person you're replying to.
Such compromises happen between companies as well when a particular app is popular. Facebook and Uber accessing private java apis which meant Google couldn't change the internals as these apps are popular.
It was a gambit used for net neutrality in 2014 https://en.wikipedia.org/wiki/Internet_Slowdown_Day