[slik]

You bring up an interesting point that he's more likely to check behind weak pairs on the river, and only bet as a complete bluff. But I believe you're overlooking some necessary information.

You underestimate the times that villain will bluff with K or J high, and call your c/r -- (not the brightest thing to do, but a certain % of the time this will happen).

Also, a certain % of the time villain could have a set or 2 pair on the flop.

The bluffing pot odds on the river are actually a little different. The pot is 7 sb's going into the river, requiring a donk bluff to work 22% of the time and a c/r bluff 31% of time.

On the turn, you are getting 5-2 on 6 clean outs to the nuts, and some more outs to the non-nut straight and weak pair outs. From your description of villain's bluffing tendencies, you can only gain 2 sb's more from him on the river (since a c/r will actually lose you money when he has a hand) making a turn call purely on implied odds possibly incorrect. For this reason it may be better to donk the river as both a bluff, to get value if you hit, and to be able to fold to a river raise if you hit if he is that passive.

All these things point to a river donk play being better than a c/r bluff play, but as you say, they ignore villain's bluffing frequency that you say depends on his hand on the river. You'd have to be extremely sure of villain's river tendencies to make c/r bluffing the river more profitable than donk bluffing, and I don't think you can do that without reasonable history with the villain. Also, like you suggest, if he checks behind with trash, you lose the pot, and in that case your turn call might be incorrect as well.