Were those really “slave-catching” expeditions? Serious question. I always thought they purchased slaves from African slave markets.
You may have a point; depends on the definition of “catching.”
If "catching" is limited to going into the interior and using pit traps, net traps, cage traps, body grips, deadfalls, and snare wires - then no.
On the other hand, a baseball catcher is said to make a “catch” simply by moving his glove into the line of trajectory - and holding on.
If Northern slave profiteers were not on slave-catching expeditions, and merely slave-acquisition expeditions, that changes everything. Perhaps Brown University can claim compete exoneration and even argue they did not receive the benefit of the bargain.