Well, look at it this way: you gave stuff to LinkedIn.

Whatever their terms say, they're storing your stuff, they are serving your stuff, and they've reserved the right to extract value from your stuff in perpetuity, according to your agreements when you signed up, when you posted, and when they updated. Doesn't matter about your privacy settings, because it all happened on LI.

I mean, you can delete the stuff you posted if you don't want future AIs trained? Delete your whole account if you didn't like LinkedIn messing with it?

(I could likewise say this about MS Windows, Apples or anything: if you don't want someone to have your stuff, give it to someone else, or don't give at all?)

But in the end, you voluntarily gave it to them, because it was free, but you are the product, and not the artist.