No one actually has to read this, I just wanted to type it out and express my thoughts. Its pretty long, haha. Wanted to mull over it in my mind.
Jesus never sinned. Jesus ate fish- therefore eating an animal is not sin. A vegan once told me "God never intended mankind to eat animals." Then I showed him the verse in Deuteronomy where God commanded the Israelites to eat from the flock and from the herd. Also a verse (I think it's Genesis 9:6) where God Himself prophesies that there will come a day (New Testament) when He will give us everything that crawls on the ground for food- just as He gave us the green herb. This means it won't be religiously wrong to eat it.
If they want to eat only vegetables, let them do so in their attempt to please God. But if they want to force this unnecessary burden on others as religious rules, that's teaching falsehood. Jesus fulfilled the Old law- that means He ate "from the flock and from the herd" without sinning.