Or maybe you're just misunderstanding what veganism is abiut in the first place.
Some people (mostly non-vegans) seem to believe it's about blindly and thoughtlessly abstaining from animals products. That's how veganism might look like from the outside but it's not actually what it's about at it's core. That would be to avoid all unnecessary suffering. Vegans are for example aware that the farming of plants does indeed cause animal deaths. But we can't avoid those without starving. So it's not unnecessary. And still vegan.
Within the same logic if someone, for whatever reason, would need meat to survive he could consume it still within the same ethical framework. And theoretically that could be vegan. The thing is: For 99.9% of people it's BS that they need meat. So obviously in the vast majority of cases it wouldn't be vegan, just a hypocrite lying to themselves.