You better have $50-100K to begin
Or know how the system works
Quite why HiFi makers would suddenly think litigation against individuals is a good idea - is unclear. Lawyers grant jurisdiction to the court/tribunal and will simply hoover up most of the benefits.
Surely it's cheaper and better to work with reviewers to improve the products.
As for little holes causing resonances, I think it's more likely that they would simply causes damping, and that the observed 250Hz bump is a measurement error or a real feature of the item tested.
The constructive response would have been to ask for a new measurement with the feet in. Instead, there were threats - so perhaps the maker doesn't think the feet holes cause the bump either... so there's that.
If the maker drags it to court, and the reviewer decided to argue in the legal jurisdiction for whatever reason, the maker may need to demonstrate that the holes were the problem, which would be interesting.
So now I'm curious to see the 'with' and 'without' feet frequency plots