The fact that your lawyer friend is a car guy, while I'm sure he might have more empathy for your situation because of that, won't lend any more credibility to your case, nor result in a different outcome.
And sure, they may state on their website that it will not affect the clear coat, but the disclaimer that Rathburn quoted above pretty much releases them of any/all liability regardless.
As already mentioned, since this was not done by a professional shop, if you're looking at it from the supplier's POV, there's no reason for them to believe that the product was not altered prior to being applied, and no real way for you to prove that it wasn't either.
My best suggestion to you would be to have a detailing professional assess the paint, if you haven't already, and see if some of that damage can't be corrected.
And who knows, maybe that would be a cost the company could be willing to help you out on. But I wouldn't be counting on them cutting you a cheque for a respray (paint, plastidip, or otherwise.)
Not too mention, that taking this to court, even if it resulted in a favourable outcome for you, would cost way more than you would ever get back in return.
Just my 2 cents! Best of luck to you!