Interesting question. I think it really depends on which purpose for the distinction we have in mind. If you make the distinction on "was/wasn't once part of an animal" then it would make sense to classify it as vegetarian - and people who don't eat meat purely because they oppose the harm that is done to animals might follow that classification.
On the other hand, if you make a biological distinction - plant vs animal proteins - then this is clearly falling on the "animal" side. This might still be important for people who don't eat meat for health reasons or who are vegetarians for so long that they find meat plain yucky, no matter where it's coming from.
Maybe making this a third category would make most sense.
On the other hand, if you make a biological distinction - plant vs animal proteins - then this is clearly falling on the "animal" side. This might still be important for people who don't eat meat for health reasons or who are vegetarians for so long that they find meat plain yucky, no matter where it's coming from.
Maybe making this a third category would make most sense.