IMHO, the workable solution is to get people to eat vegetarian once in a while, eat less meat in general (which is even good for one's health, as at least in the West people eat way more meat per-day than recommended) and turn eating beef (and, to a lesser extent, pork) into something that is more unusual than usual.

Reduction and more climate-friendly meat consumption is way easier to sell as an idea to beings who are omnivore (so have a natural desire for the stuff) than full vegetarianism (or, worse, full veganism) and I'm pretty sure some of those people will end up mainly or even totally vegetarian and even vegan, as they get used to and appreciate meat-free meals.

However the Moralists are as usually abusing and distorting a genuine concern to push an absolutist view (as it's anchored above all on a Moral viewpoint on meat consumption, so Environmentalist objectives are at best secondary), damaging the actual Environmentalist outcomes since it's a lot easier to both convince people to slowly rebalance their meat-consumption and have it happen in a safe way for even the less informed than it is to do it with sudden total abstinence.