Griffey what you're saying makes lots of sense.

Reason I think calling is o.k. is that villain isn't a robot and will react differently to a lot of different river cards.

If he's got the balls to shove the river when a spade hits then all the power to him. But that's one of the reasons that calling with a river plan can be best even if it seems illogical. Villain's line doesn't make a whole lot of sense to me so I want him to continue with his bluff if he's got crap. Don't forget that my line looks a lot like a spade draw so unless he's completely maniacal, he'll very likely check a spade on the river unless he has the flush himself, meaning that I'm not necessarily losing the pot just because a spade hits.