It isnt a holiday. It is the government trying to shame people into changing their culture and swaying the economy toward a specific political outcome. I get a chuckle that the cattlemen took up the challenge and are throwing it back on him.
Honestly I dont really care about this particular hill that Polis has staked, but I really dont care for the methods. You can say "what is the harm" and for this one I would agree, who really cares. It is the precedent it is setting, that the government is openly promoting particular lifestyles and picking winners. Lets take it to an extreme, consider if Polis announced a Gay Only Day where everyone was expected to have romantic relations with someone from their own gender. Would you participate in that? I suspect that might have much more pushback but in essence it is the same as his no-eat-meat-save-the-planet day. And yeah, I would be saying the same thing if it was a republican governor promoting some conservative political talking point made up "holiday".