DY:
1. There’s no reason to think that Reuven might not be someone who holds from the very widespread shitta that Cholov Stam is Cholov Akum mamish, and hence completely prohibited to consume.
2. There’s nothing twisted about the point of a baal nefesh.
3. Rav Moshe’s shitta is even stronger since he is only mattir bshas hadchak, and there’s nothing indicting Reuven is having a shas hadchak.