Bad ol' Squeezyjet
First off, +1 for the Free Speech bit. Unless he's breaking any laws (in which case you should involve Plod) then he has every right to criticise as much as he wants.
My own experience with Squeezyjet was similarly crap. A family group including myself were checking in for a flight from Gatwick to Ireland for a funeral and rocked up to the check-in desk at some ungodly hour of the morning.
Me: "Good morning, we're on the "oh whatever it was" to Dublin this morning".
Squeezyjet Gimp:"Good morning sir, hmm, I'm afraid I have some bad news for you this morning" (wink,chortle)
Me: "Really, and just what might that be?" (starting to get annoyed)
SG:"Well sir, I'm sorry to have to tell you that not everybody will be able to get on the flight today!" (pause for effect, then laughs).
Me: (fixing him with a Paddington Bear stare): "I don't find that especially amusing, particularly as we're all travelling to a funeral today. Are you denying boarding to any of our group?"
SG : (looking suitably crestfallen): "No sir."
Me:"Good, then perhaps you'd like to give your pathetic attempt at humour a break and get on with what you're supposed to be doing which is checking us in for the flight, if that's not too much trouble?".
I didn't feel sorry for him at the time and I still don't. Some things just aren't funny and boy did he pick the wrong group of passengers to joke with about denying boarding .