Best to get all your ducks in a row first Malc. An expert examination and report that supports your case is pure Gold - however, it would have been helpful to bring it to the dealers attention straight away.
Many franchises have substantial case studies (supplied by the manufacturer to their trained dealer staff) to refer to for paint issues - insects, impact, poor adhesion, contaminants and so on. It is hoped that the dealer inspected the paint using a qualified technician who is well versed in such matters. If so, a written report from them stating categorically why it doesn't come within warranty would be required. Then, it should be compared to an Independent inspection by your chosen expert.
Should the cause be an external influence of any description (other than something that the paint finish would resist) then it would not be warrantable. In that instance it would be incumbent on the owner to prove that it happened prior to delivery - and that could be tricky.
Escalating the issue with threats would seem counter-productive.
I note Steve says it is either at work or in his garage - it has NEVER had a journey outside of this? At work is it parked near a railway as the metal filings from their brakes can cause damage.
Regardless, I hope Steve achieves a favourable outcome.