if "we were serious" about what? the issue of foreign control is not relevant to domestic companies. we could have some other regulations too, sure, but this one is reasonable.
I think people should be able to decide which social media apps they want to use. They're not even close to reaching the levels of the "infrastructure" box you're forcing them into to justify this decision.
TikTok isn't "infrastructure", TikTok is software. TikTok exploits the infrastructure of the internet across the world, it is not infrastructure itself. The servers TikTok runs on is technically "infrastrucutre", but those same servers could run anything else, the hardware is not "TikTok". I could run "TikTok" the software on any hardware, even if it isn't connected to the public internet, and that would not qualify it as "infrastructure", at least not in the sense that it's servicing any population.
> let adversarial countries own and control communications infrastructure
This is an exaggeration that a social media platform for short form content is communications infrastructure, akin to a cell tower or fiber optic line. I'd the say the same for your mention of ITAR in a thread about, again, a social media platform.
If we were serious, there would be regulations for all social media, not just forcing of U.S. ownership then saying "all good, this can't be bad since Americans own it"