TikTok doesn't want the data of the average person becaue they aren't valuable in any way.
TikTok is being blocked because they can manipulate their algorithm to feed influencers to them that push pro-Chinese stances.
Imagine a hypothetical hot war between the US and China where China is telling a significant number of the US population what to think. I specifically say it that way becaue I don't believe any US company has a significant user base is China.