He attacks other chefs that have no talent. Much like Eminem would attack other musicians that have no talent.
The big difference is, a lot of the public knew the people Eminem attacked were talentless. In this case, most of the public knows nothing about food, and couldn't tell you who, and who is not a good chef.
He also more often then not attacks celebrity chef's, who were never actually chef's outside of their own family restaurant, or were created by a network to act as if they were a chef.
He has also no problems with wealthy people, and openly admits in his layover episode of NY after visting the LES, that he is indeed one of these upper west/east side douchebags now.
That said, he dislikes vegetarianism because he views it as something that is not only scientifically inaccurate in it's health goals, but morally shady in it's societal goals. As he points out with evidence in his book, there is more damage done to the environment and animal habitats by many of the foods eaten by vegetarians, than buying a cut of beef from a farm or ethical butcher. I have yet to see him lose a debate against a vegetarian.