I disagree with that. You're discounting the instinctual and emotional part of the game. Defenders aren't just a bunch of robots out there. If you don't think a team has effectively run the ball 70% of their snaps is more likely to get a defense to bite on a play action than a team who runs it effectively 20% of their snaps, then I don't know what to tell you.
Ok. Then you don't know what to tell me. I can live with that. Defenses try to stop the plays as they read them, as hard as they can, without regard to whether they're reading run or pass.
Now, let's say you have a running QB, making the run/run/pass decision more difficult for the defense...I imagine that has a significant benefit in terms of play action effectiveness. But that's because you have a combination of running and passing threats and because the passing threat can stay alive as the play develops, putting the defense in a more difficult position. But it's still a function of their keys and reads and not the case that they're filling faster against a run because they suspect it's coming.
That said, I'd be interested in seeing the data on the topic. I wouldn't be completely shocked to see it turn out to be the case that play action passing is more effective for good running teams (that does seem intuitively likely). If that were the case, though, it would suggest there's another area of correlation between an effective running game and an effective passing game, and it's been demonstrated repeatedly and convincingly here that that correlation doesn't actually exist.
