Forcing a sale of TikTok so it's not foreign (with a punishment of banning if they don't), especially while making no such law for U.S. controlled competitors, is no more an infringement upon free speech than introducing a tariff or trade restriction on German-manufactured printing presses while leaving domestic models untouched.
Why doesnt google or meta operate in China?
That said, so long as you don't have data centers in the country, what can they realistically do to stop you if you have a VPN?
There's nothing illegal w.r.t a private citizen trying to circumvent censorship afaik. If you're trying to use illegal content or services (hitmen, drugs, child porn, non us compliant crypto such as finance etc), then I can see the retribution, but unless you go full middle east/CCP people will still get access to and repost it
That would likely be unwise, but it would be a legitimate use of authority.