At this point, things are looking desperate enough to take the risk, so yeah, he'll pursue the answer.

Okay, so would he have likely picked up Merge on his own just from knowing it exists and generally what it does, or do I have to wrangle a teaching thread with Yuuki/Right (there are a couple threads I could turn to teaching a thing)

Because if he knows Merge (and I want to have actual!Lupa pick it up anyway) that's the next step he'd take.