What Flock names the relationship in their contract does not make it one, as the courts do very much duck type.

Flock knowingly collects PII of people they have no direct relationship with, and transfers it to third parties. If that transfer, which Flock seem to gain from, is legally a sale is something to be argued at a great expense in front of the court.

But regardless of that definition, I so think that any reasonable person (= not a corporate lawyer) would consider there is a sale of data here.