Eventually, I can see these hearings continue, but the line of argument will change to protecting American jobs, especially if Meta's ad revenues fall.
The FBI chief being discussed here, Wray, is a political appointment but not an elected politician so hopefully the appointment shields them from politics. Nevermind that the DoJ tries pretty hard to be independent of the President. But beyond that, this particular chief was appointed during the previous administration of a different party. And has served in both party's administrations.
I have no position on TikTok, but Wray saying this is not really comparable to McCarthy.
In fact the McCarthyism acticle on Wikipedia has a whole section about the FBI. The FBI was deeply involved in McCarthyism.