"So, if a team picks him up, they have to accept his real limitations and balance that against his PR nightmare circus and it adds up to squat."

Reality is, it's a talent situation. You mentioned Ray Lewis, he was in far worse crap than Kap, and the NFL looked the other way, Ray was a hell of a LB, talented.

You got Aldon Smith who might be certifiably crazy with the stupid crap he's done, he's suspended, but teams would pick him up right away once he's off, heck, he might still be on the Raiders roster. Again, Smith is talented.

If your talent is worth it, the NFL will give someone a ridiculous amount of chances and teams will pay you. Kaps talent level isn't worth the PR shade that would come with him, so he stays unemployed, it's really as simple as that.