He sure appears to be belligerent in the latest video - not.
Based on dozens of comments in this thread, it would appear that there is a culture within U.S. airlines of "we have always done it this way," and "it's not in our CBA," and "f**k the SLF/paying public. I make $3-400k/year, so screw them."
"Thinking outside the box" is, well, outside their comfort zone. Maybe they need comfort dogs and safe spaces.
I also suspect that U.S. airlines have been kicking compliant passengers off airplanes (post-boarding, i.e. in their seat) for so long that it has become acceptable, even though likely illegal and certainly contrary to their CoC. This practice has come to light because of this incident. Someone had the guts to say - NO!
They either have to set their computers to default to permanently reserve four seats on each flight, and use the tried and true "standby passenger system." If the four seats aren't utilized by DH crew, then let the standby passengers have them.
Or charter.
None of this will work of course, because it is outside the box.