Slide wall construction and damage question

Finally was able to get her down to the shop today and the body shop manager had a look at it and his opinion was to leave it alone and that it is cosmetic in nature only and caused by heat build up. He also says that many units he sees with aluminum framing and the plastic outer panels have the same issue as mine. His reason for suggesting not fixing it was that they would need to pull the slide out for the repair and he would rather not mess with the factory sealing of the slide. His comment was that once the slide is removed and reinstalled there is a chance that the unit will never seal as good as it does now.