He seems to largely be in denial.

If he really was fired for sleeping in class, an appropriate response would be, "I feel that I was fired unjustly from Mesa. Nevertheless, I've learned that one simply shouldn't appear to sleep in an airline class, even if it's a break. I'm going to put this behind me and do the best I can to explain to future potential employers what I've learned."

If the harassment allegations are true, then he's clearly in denial about the whole thing. Now, it's also possible that his behavior was actually acceptable by most standards, but one FA complained about him for whatever reason, and the company fired him to avoid the very real possibility of a lawsuit from the FA that could run into the millions of dollars. That, too, is possible.

In which case, the correct response from the OP would be something like, "I feel I was unjustly dismissed from Mesa due to a misunderstanding. I feel I was falsely accused of sexual harassment. That said, I've learned that my behavior must be beyond reproach at all times in a professional situation. In the future I'll be extra careful to avoid even the slightest hint of impropriety. I'm disappointed that I had to learn this lesson in such a manner, but I hope that I will be able to satisfactorily explain this to future potential employers."

Instead he's blaming everyone else but himself for whatever happened to him.