I'll post my take on it...
Firstly, they're not doing anything illegal. Vender price fixing at an event doesn't violate anti-trust laws because there are other events that provide the same overall service. There is still competition in the market as a whole. Now if the PSP was the only outlet for paint manufacturers to sell their goods it would be a violation. This isn't the case, though.
Is it good for the customer, or even moral for that matter? No, it's not. But since the marketplace as a whole provides other outlets for this sort of entertainment you, as a consumer, still get to vote with your wallet. If the price fixing at these events bothers you so much you can keep walking and attend another. This is what the anti-trust laws are meant to provide you with: options. And you still have them, so no big deal.
As to the drama surrounding this, that's likely just personal issues getting in the way of business. Gino's stirring up a stink because he's not getting his way. However, as far as I'm concerned the PSP is not out of line requiring that you not sell to the opposition if you want to vendor at their event. Now, if that's not something stated in a contract somewhere, and their vendors are selling at the NPPL as well, we know there's some truth to Gino's accusations. And I'm sure there is, but knowing the two sides of this issue, the pot is likely being stirred by both hands.
But the specifics are missing. I've not seen a vendor contract, I don't know what other agreements are on the table with the existing vendors, etc, etc. There are many factors that are missing. It could be that Gino never even applied to vendor and he's just stirring the ****. I don't know, and neither do the rest of us. We can only comment on the legal aspects of vendorship, and then we don't even know if they apply in this instance. So it's all speculation.