It’s hard to say if Anthony Bourdain was really a nice person in real life because I did not know him. After he died, many complimentary tributes were made about him, not just on Twitter but also on a special CNN show called “Remembering Anthony Bourdain”.
However, most of these tributes talked about his work and not a lot about what he was like in real life. Also, the website TV Cheat Sheet includes Bourdain in its article “These Popular Celebrity Chefs Are Really Mean in Real Life” but it does not give any facts to support its claim.