> Their preference to shut down instead of receiving tens of billions of dollars would be a clear violation of a company’s fiduciary duty to shareholders for any normal company.

This is not strictly true - when a company leaves a huge market, it is imprudent to leave behind a well-resourced competitor in place. If I were a ByteDance shareholder, I'd hate if it spun off TikTok America LLC, and then having TikTok America compete against ByteDance in Europe and the Rest of the world on an equal technological footing, but perhaps even deeper pockets from American markets.