In general, I wholehearted support the freedom of speech, and if it were any other case, I would agree with the EFF statement here. However, knowing how the sausages are made, I am reluctantly agreeing with the ban, at least for now.
People underestimate how powerful these tools can be. Based on simple, readily available "anonymous" data, we can already impute your demographics data -- age, gender, family relations, occupation, income, etc -- using a decade-old ML techniques. In some cases, we can detect which stage of your emotional journey you are in and nudge you towards our target state. What surprised me about Cambridge Analytica was its ineffectiveness, at least as reported. There are plenty of teams out there that use these techniques to greatly further their gains, whatever those may be.
In Primakov doctrine, information warfare through sowing discontent and/or eroding psychological well-being is very much real and actualizable. I am not claiming that a foreign government is currently single-handedly controlling TikTok to brainwash the American youth; we do not have conclusive proof of that. However, the fact that such a tool is in a foreign country's arsenal is itself a massive danger to America's national security.