In hindsight, you're exactly right. But nobody sits there and deeply thinks out everything they say, and as such there's no way to know which are gonna randomly set off the BLF hate-squad. It seems a lot more reasonable to just expect everyone not to overreact and understand that jokes are not serious.
i think the point where it starts being serious is where you actually begin to take on discussion. if you had said at the time "yeah dw guys it was a joke no worries" this might have turned out differently, though it doesn't seem like you intended the initial comment to be a
complete joke
i really don't think anyone actually cares if someone is vegan here. the only problem comes when they feel pressured to concede that the way they eat is morally incorrect, which they aren't going to do, hence this thousand year stufffest