[Grease]

I think its fine.

You lost to a player who completely misplayed their hand, and I think that laying this down on the river would be a total disaster, barring a huge tell or him flipping his cards over in a fit of glee.

The only way you could lay this down is the player who is so LPP is that a river raise means at least a set, and there are players like this out there, but it would take huge disipline, and you'd have to be almost positive he would never raise with a rivered two-pair.