The innocuous tweet spurred backlash. A man named Anthony, who goes by @7AnthonyDagher7 on Twitter, posted images of @itsallzara's tweet and direct messaged her, criticizing her for purchasing ice cream -- an animal product -- for the little girl. He also posted screenshots of their exchange, for transparency's sake. His initial tweet garnered 1,500 retweets, apparently after reaching an audience ready for a scrap.
Reading through the messages, you'll see that Anthony, who is also vegan, thought it was wrong to buy a child non-vegan ice cream, only because it perpetuates the unethical treatment of cows used in the mass-production of milk products: