I read that the mfgr has to prove the aftermarket accessory caused the malfunction. Nothing about a pro installing it. Dealer is feeding you a line of BS. Who would wire the sunroof to anything that has to do with power steering. You might go by the place the put the roof in, ask them to spend 5 min showing you where there wired it up so you can tell the dealer he's full of it.

"Hybrid Owners Do It Both Ways"