Everyone keeps making religious connections, but it’s worth pointing out linguistically most countries in Europe (and the world) refer to red meat, poultry, and seafood as entirely separate. Meat often just refers to red meat. English is in the minority to bucket them all under “meat”
Not to mention that loads of people detour through pescetarianism on their way to vegetarianism. But even if you stop at pescetarianism that's still a wild improvement on plenty of metrics over eating other meats.
There seems to be this pressure to either go fully vegetarian or it doesn't count, which is obviously total nonsense.