I find PbP, forums, texting, Facebook, and social media are strange sometimes. There is no tone or inflection or in person body language to read. Simple Jokes or Disagreements can get blown way out of proportion. I once made a joke through text that turned into basically a two day argument with an ex, it didn't matter that I was joking, the damage was done.

But yeah the DM can kick players as they see fit. It's not fun DMing for someone you don't like and it's ok to not like people.