True, classes are metagame concepts, which in turn means that wearing a Monk's Outfit is not a sign of weakness because there is no "monk" to be weak. You can get armorless, not good with weapons, maybe a few more characteristics that haven't yet come to mind. A Sorc 4 or whatever isn't actually going to be useful (so it's just a meatshield) and the dragon, in all likelihood, won't be able to tell the difference between it and the adept. Saying you effectively get a miss chance is fine; saying the dragon will avoid the Adept, specifically, is not. Though in a few levels, this will become dramatically less useful a strategy once the discerning dragon (IE anything but a white) can get arcane sight permanencied on itself, and quickly notice which of the creatures invading its home is the most blinged out. That is more of a high-level thing, though.