The US has consensual access to pretty much every major player in the social media marketplace

I believe this to be true, yes. (It's acknowledged that they have access through subpeonas, and personally I think they have active spy operations in pretty much every major internet community including Tiktok. They have active spy operations in actively hostile foreign governments, and compared to that, getting clandestine access to a large internet community is child's play.)

(as we know from the Snowden leaks)

What part of the Snowden leaks? The big things I'm aware of Snowden revealing were massive efforts to capture and store phone and backbone raw-packet data, partial compromise of TLS, and another massive effort at compromising email. Then there were some other more minor specifically targeted things, but I didn't see any social media in those. Can you send me a source on this?

Until TikTok opens itself up to US surveillance

I think I spent a pretty good length of time documentation and explaining why I think that these rules do not represent opening up Tiktok to US surveillance. Y'all keep repeating that these new rules represent opening up Tiktok to US surveillance, and then riffing on from there the further conclusions. If you want to talk to me about this, can you back it up a little and say why you think these specific rules represent surveillance?

E.g. the NSA (according to rumor) installed their hardware decades ago at some AT&T backbone sites, with consent of AT&T. When Verizon later became a major player, they tapped into major Verizon backbones, without the consent of Verizon (as was leaked by Snowden.) Both of those are surveillance. What they didn't do was get involved in AT&T's terms of service, ask for the right to veto hiring certain executives, conduct audits and assessments of AT&T's operations... because that's unnecessary if what you want to do is surveillance. You just surveil. Why, then, are you saying that when the US wants to do those things to Tiktok, that represents some kind of surveillance?