Why do senior leaders make the brig seem like the worst place on earth?

Don't really understand why you are even posting this. You often hear people say bullshit like " Send me to jail... I don't care,, Jail ain't shit!!" These are people that have absolutely no will to succeed in life. If your idea of being a success is having a hot and a cot and a 10 X 12 living space be my guest.
I've lived in situations that weren't much above those in a brig, minus the guards. I have froze my ass off and been soaked to the bone and stayed up all hours of the night while brig rats were warm and cozy with full bellies.
One thing I had that they didn't. Pride in what I did.

Anyone who thinks that jail is fun or not the worst place to be is going to be spending a lot of time there for the rest of their life. I have no inclination to ever go to jail. Ever. I've heard about it from my ex husband. He's spent quite a bit of time in prison (minimum security) and jail...it doesn't sound like fun at all. I much rather enjoy my freedom and ability to get a job.

This is one of the more painful threads to read.
I just can't... but what the hell. I will try anyway, for those who may read this for posterity.
The brig, or any military confinement, is not a good place. It is not fun. It is not a club med. It is not what there was in the old days where you'd be busting up rocks and taking a flogging, and there are recreational opportunities to keep idle hands out of trouble and educational opportunities to help make a productive member of society afterwards, but go there and you will be behind the eight ball for life. Don't get into this situation, if at all possible.

Now as for this particular individual, if I follow the story, he was accused of some stuff by his spouse (not unheard of) and the CO tossed him in the brig to cool his jets and deescalate the situation while they investigated. So far so good. The charges are found without merit (or short of evidence, or some such) and dismissed. Then he decides to go sideways and get in arguments with superiors - something sure to bring the green weenie in for a poke.
Now you have transitioned from wrongly accused potential rehabilitation project to mouthy malcontent with authority issues. The USMC says thanks, but no thanks.
Then, in the service determination phase of out-processing, this young man goes against all sense and any counsel he would have had and accepts an Other than Honorable because he was "impatient" about the process! I suspect that what he was impatient with was the details, extra duty, and general military comeuppance that comes around when you are judged insubordinate and on the way out.
That was a very unfortunate mistake on his part.

It sounds like he's landed on his feet and has a job lined up, so I wish him luck.