or installing a great firewall to prevent US citizens from accessing their site.

Literally no one is suggesting this, but keep firing yourself up I guess.

Right. So if they sell ads on it, it's not a speech platform right? Reddit, not a speech platform? The Washington Post? The Guardian? Lemmy, when lemmy instances start running ads, Not a speech platform? Gmail? Not a speech platform?

It’s not a speech platform, at best it could be loosely defines as “press”. Even if I’m generous and concede that, pretty sure there’s Supreme Court precedent for allowing the government to block the publication and dissemination of foreign press. Also no, Gmail is not a speech platform in this context lol.

It's my ability to use the speech platform that gets banned in the process.

You need to stop picking the things in my comment you want to argue with and ignoring the rest. The First Amendment prevents the government from criminalizing or penalizing you, an American citizen, from engaging in protected speech. It does not prevent them from forcing a foreign company to divest or cease local US operations. Doing so does not infringe on your speech. Infringing on your speech would be something like criminalizing the act of downloading a tiktok apk and using the app after ByteDance was forced to shutter US operations.

You see the difference right? You’ll still be able to use TikTok after the (probably not happening) ban without any criminal or civil liability. If ByteDance says fuck it and geoblocks the US, you still haven’t been blocked from your speech by the US government, you’ve been blocked by ByteDance, and if you felt like suing them in China you could full send it if that was for you.

They can ban TikTok from being able to "do business" in the US, that is different from pulling it from the app store

Ban TikTok from earning any revenue in the US and they will pull the app themselves. Do you think TikTok is a charity or a non-profit or something?

And frankly, "doing business" has been an inherent part of speech platforms for decades, selling advertising on speech platforms is how they can exist, all the way back to the days of newspapers and radio.

Sure, press publications sell ads, no one said otherwise, not really sure what purpose stating the obvious serves. Ultimately, the US government is under no obligation to allow a foreign company to offer goods or services within its borders, regardless of whether it’s a “press” good or service.

To recap:

1. Banning tiktok does not ban your speech specifically.
2. As no entity protected by the Constitution is being censored, the government isn’t violating the Constitution.
3. There is no 3, that’s it. Congress is free to swing the ban hammer.

Unless you think that the Constitution applies to everyone in the entire world, in which case I guess I’ll need to buy some stock in Northrop and Lockheed.