I actually think it's a really really positive reaction. I also think that Armand's recent statements that he may never sell OGV for offsite again comes down to the same thing.
There's something wonderful about Zwanze Day - more people get to try a unique lambic every year than ever before. I've been going since 2011 and have gotten to try many awesome lambics that otherwise I would never have had access to.
I've gone on and on (and will go on and on in the future) about the supply and demand problems in craft beer (and how imperfect of a market this hobby is). Because supply is so much lower than demand, price needs to go up. But there's more than one way to modify price, and raw dollar amount is not the only tool that these brewers/blenders have. Ability to restrict how supply gets out is another way to solve the same problem - this way, JVR or Armand or whomever can charge a number that they don't find repugnant, and still ensure that secondary marketeers aren't profiting off of their hard work.
If a LOT more breweries began following this model (massively increasing on-site or otherwise restricted availability and eliminating secondary market opportunities), the benefits would be enormous. Right now, there is a "secondary supply" constraint in that so few opportunities exist for things like Zwanze Day that if you miss it, you miss potentially your only opportunity for a unique experience. But if top tier breweries did this kind of thing frequently, you'd miss many but enjoy many as well. Meanwhile, secondary marketeers would fade away as overall demand for unique experiences would be (more) satisfied by such events.