@aral I think the better question might be, did anyone think the data collection ever stopped https://en.m.wikipedia.org/wiki/PRISM_(surveillance_program)
Maybe they were actually trying to get their hands on pegasus to reverse engineer the zero days that seem to be exploited in WhatsApp to patch them. It seems far fetched to me that anyone, even a FB employee, would believe that using this kind of tool for targeted advertising would be a good idea.