He certainly should have NOT gone to the mfg first, and should have pressed the dealer responsible hard, all the way up to the ownership as you say. Including making clear that he will seek resolution even if it means the courts.
However, i don't see it as unreasonable to go to the manufacture after failing to get resolution, but before filing suit. The manufacturer SHOULD be his friend here, assuming he is coming to them from a reasonable perspective.
They are clearly not obligated to do anything - but they also have a clear vested interest in happy, honestly-treated customers. Having dealt with a similar problem in a different industry - when approached politely but forcefully with the facts of the situation, the mfg did "inform" the dealer that they "would" make it right for me, or there would be some sort of repercussion in their relationship.
The dealer came around, fixed it for me, end of story. I didn't have to spend 10's (or more) hours taking them to court. (notably, presumably here the actual 'damage' would fall under the small-claims limit - so he can do it without thousands to an attorney; but not without a LOT of time invested)