There's an easy fix. Just extend "Know your customer" to the ad industry, including all parties who engage in the creating, buying, selling, distribution, aggregation, or display of advertisements. After the last decade of mergers and buyouts, the last remaining large scale ad companies would suddenly find it too risky to carry this crap. You need only look at how to banking and financial industries routinely turn down opportunities due to KYC.

We just need the political will. Or, pass a note to some easily lead senators that ad networks sponsor terrorism, or whatever the fear-of-the-day-is.