if he's a real bluffy type then just call and don't fold no matter what comes on the turn
be very careful about making labels like "mubs" play that you then let guide your decisions... (those 2 example folds you gave actually pretty good folds if he sees you as solid tag)
fwiw, i would show him my hand this time, say impressive fold or something like that, and planning to really put the pressure on him in the future with semibluffs and bluffs, if you don´t already do.
i know it is harder to bluff than to valuetown somebody, but we gotta exploit him.