The core problem is that the reason of removal is not based on fact, but just plain racism. They're not even trying to hide it either. If you've been paying attention to the intelligence community, they've been trying to drum up a justification for a war with China for awhile now.
Well the question isn't about taking China seriously, but admitting that China was right in the first place. US's argument is that China can spread disinformation on Tik Tok, which is exactly what China was saying about Facebook etc... So, China, which doesn't have freedom of speech banned those sites for promoting foreign interests. US is now trying to do exactly the same to Tik Tok.
IF you accept USA's argument here, then you implicitly accept China's argument since they're the same argument. So, again, it doesn't matter what China says, what matters is what you just said:
It’s kind of hard to take their criticism seriously when western sites and apps like the BBC or Instagram are blocked in China.
So there by admitting, China was right, countries SHOULD block foreign influence.