I was hanging out with a women I went on a few dates with in the early 2010s. I was taken aback by her bad takes that evening, especially the body shaming and gossiping going on about mutual friends. She asks me why I'm vegan and I'm like "oh I went into a slaughterhouse once before, you can't believe...". And she interrupts me "Oh please don't tell me!" Honestly this woman if fine. She's not evil, just a bit bougie and lib. I've met much worse though.
I can't get over all the women I've dated that have been super anti vegan or vegetarian, they were kinda shitty about other stuff later on. At the time it was shitty to fight with and lose someone who I cared about and spent a lot of time with, but in hindsight I'm so lucky they're gone. Quite a few dates I've been on have been fine or positive about veganism, and our friendship has stood the test of time.
I'm sure this is just true for caring about other oppressed groups. Like if a date didn't give a feck about Palestine or queer people, they probably suck. I'm honestly sorry for people that date men, as so many of us have terrible convictions.
Over time I've found that slaughterhouse talk is just very off-putting to non-vegans. Yes they enjoy the fruits of indefensible acts of torture and murder that would give them PTSD in five minutes if they were witness to it. People are very good at compartmentalizing this if they've been omnivorous since they were born. There is an endless parade of horrors one can find in this world inflicted on both animals and humans. I would not bring any of them up on a date.
If you're actually compatible with an omni (it's possible!) veganism is a sexually transmitted infection so it's probably the best way to convert people anyway.