I don't have an opinion about the PKK. My broad take is: if Europe doesn't care, there's no reason for the US to be leading a sanctions effort. I'm confident like everybody else that this is largely pretextual.
All I care about is the claim that if they can do this to A/I they'll come for Signal next. That doesn't follow.
Many EU governments care, because Turkey cares, but the problem is that Turkey's position that they're terrorists is legally iffy, so a lot of European courts disagree, and this creates a schizophrenic situation where politicians hold that they're terrorist and will claim that it's the government position, while the actual government position in the courts is that they mostly aren't and that it's a case-by-case question.
All I care about is the claim that if they can do this to A/I they'll come for Signal next. That doesn't follow.