The First Amendment case would be much clearer if this was actually about banning access to TikTok (it's not: TikTok self-blocked US users, Amazon/Oracle shut off servers, and app stores stopped distributing to US users). TikTok could choose to operate their service (like many other Chinese companies) using only non-US infra and without relying on American companies to distribute their app; indeed, the Chinese version of TikTok, Douyin, hosted entirely from Chinese servers, continued to work just fine.
This case is also a reminder of why the iOS App Store is so bad for rights: at least on Android, you could sideload a 'banned' app; Google can comply with the law and US users can still download TikTok. On iOS, you don't have that option.