I would say they're technically not data brokers because they collect data directly from an agreed upon relationship with a consumer, and they do not sell the data itself but rather productize it for advertisers.
But there's no evidence that the information they gather on non-users is shared with third parties, even in indirect ways like the ad-targeting information. (I don't necessarily reject the term "shadow profile", but it's important to remember that it's an activist term; there's no reason to expect that they have similar formats or uses to the non-shadow profiles.)
Presumably they get the data for the shadow profiler from tracking scripts and stuff that run in your browser, so technically that’s a relationship you accepted when you ran their script and allowed it to phone home.
