"Don't 'yuck' someone else's 'yum'" doesn't mean you're wrong to be personally grossed out by something that someone else is into.
It does ask you not to project your reaction onto that person ("you're gross"), or onto the fact that they are into that thing ("liking that is gross"), or to moralize based on your reaction ("it's wrong to like that.") And especially, it exhorts you not to do any of those things vocally, let alone from a platform.
Having a 'yum' is joyous. Celebrate joy.