Then when they assimilated Picard and found out it was the work of Q, they probably thought "Okay they didn't do any of that amazing stuff but they must have some importance for that Q thing to be interested in them."
Works for me. They might have knowledge of Q, and are desperate to assimilate him. Picard and humanity are bait.
Oh my goodness, you just may have resolve an argument in the movie forum about how to get Q into a TNG movie.