I think you are on the right path.
I believe its Josh not vocalizing to Dorsey or QB Coach or WR Coach etc in support of what Stef wants to say about the offense.
I don't see Stef getting upset if game plans are working and the Bills are winning even if he doesn't get the ball.
But when CB's/Safeties say the offense was predictable (IE Vikings Peterson saying that) , and Stef telling Josh like yo, we need to change ***** up and Josh just following what the OC is saying, I can see the frustration.