I saw PSL recruiting at my local event, but they didn't really try to coopt the thing as a whole. Basically, they seemed to talk, kept their speeches mostly to stuff everyone agreed about (Wallstreet and Trump is bad), inserted some anti-imperialist talking points, and then used that to find receptive people, and sign them up or hand them flyers.

So, they were selective about it, but it doesn't mean the protests weren't useful to them. It's a chance to grow the movement and get people who wouldn't have otherwise heard of them. I'm sure other communist movements did a similar thing.