That is as ridiculous as those that dismiss catholics out of hand as nothing but cultists.
If I believed Protestant worship to be true worship of God, I would be dishonest in remaining a Catholic.
BTW, that isn't to say that Protestants don't intend to render true worship to God (and intention does count for something), merely observing that they objectively don't. Hence PM's confusion between Marian veneration and Mariolatry: Protestants worship God by prayer, singing songs, and listening to sermons; if a Catholic prays to Mary, sings songs about her, and listens to a talk about her, the Protestant concludes that's "worship" because that's what he calls what he does. That isn't what I call "worship," however, and I would not be rendering true worship to God if that were all I did concerning Him.
I'm denying PM's premise.