Partner was thinking along the same lines as jmcw and masse24, albeit even slightly weaker:
Down one on a heart lead. I didn't agree with partner's choice for two reasons: I think this West hand is within the parameters for a second-seat unfavorable preempt (although certainly max), and because it's perfectly suitable for notrump if partner has the other suits under control and a spade. That's the main reason, I suppose, that I don't buy into the description of 1M-2X-4S advocated by some here; even if it's extremely descriptive, it blows by a not-unlikely good spot. It makes more sense to me to have the bid
deny a solid suit, maybe something like KQJTxxx QJx x Qx, but even with that hand I would prefer a different route. I guess I agree with those who think this auction shouldn't exist.
That being said, I think the result is my fault for not passing. With no agreement in place I should have played it safe.