The crew, i have no doubt did not in anyway overstep their authority,
Well, you can't have it both ways.
You can't demand a pax get off just so staff can get on, threaten pax with LEO, contact LEO...... and then say we are not responsible for what happened next. The airline appear to have started this chain of events by deciding he needed to get off so they could get staff on.
As the CEO has confirmed, the airline can't kick someone off if s/he isn't doing anything wrong, and he has undertaken this won't happen again. So someone did overstep. Most likely that person believed they were correctly following policy and enforcing the rules....Only they weren't.
As stated previously, this escalated out of control because everyone focused on their rights and authority, and overlooked their responsibility and common decency.
The pax should probably have handled this better. But the general expectation in a customer service industry is that the professional staff should (and will) be held to a higher standard than an individual customer. Don't accept this? Simple, don't work in a customer service industry.
Anyway it appears this is just about all over. The court of public opinion is the fastest court in the land. Everyone simply needs to agree how many zeroes on the check.