[randallscott35]

"But while I applaud his using the PA to deliver his expletive-laden rant (not really), and have absolutely no problem with him taking the beer as his parting gift (some guys get golden parachutes, others get golden hops), his deploying of the emergency slide is completely indefensible. There are all kinds of dangers associated with launching one of those slides, not the least of which is to the people on the ground. Someone on the ground could have been severely hurt, even killed, if they happened to be under that slide when it deployed. And there are all kinds of people—and vehicles—around a plane as it comes into a gate: ramp agents, maintenance personnel, plane provisioners, fuelers and fuel trucks, luggage carts.
Secondarily, though probably less important to most people's way of thinking, is the cost and inconvenience of this action. Those slides are like the airbags in your car: they're used once, and they're done. And also like your airbags, they're incredibly expensive. More irritating, at least to the people on the next flight, is that the plane had to be taken out of commission, at least for the rest of that day. That plane was supposed to go places, people had tickets and schedules, and that was shot to hell. I'm sure the plane had to be photographed and investigated by the FAA and the NTSB, meaning it couldn't be moved until their their investigations were satisfied, which takes a gate out of commission for (probably) a day (at least). At a busy airport like Kennedy, that's a huge issue that creates a domino effect.