Basically, USCCA is an insurance policy. It is not a guarantee of legal representation.
As such, they are prohibited by law of providing coverage for any criminal act. Some of that is common sense, like the case they mentioned where the woman was convicted of murder in a pretty clear cut case.. no coverage.
But... the kid that shot the douchebag prankster at the mall.... well, it was illegal for him to have that gun in a mall. It doesn't matter if the shooting was self defense. He was a criminal before he drew his gun. A lawyer doesn't give a shit. An insurance company can not pay that guy anything, by law.
So... how could this screw YOU. Bad guy breaks into your house to do bad things. You have an illegal hi cap magazine in your Glock. No coverage for you.
You shoot him with your AR-15... with a telescoping stock... No lawyer for you.
Or maybe it was New Years eve and you were wasted. They could deny coverage.
But for me, the biggest issue is that they will deny you any benefit if you take any plea. You shoot someone in self defense, prosecution offers to reduce the charge from say manslaughter to some pissant misdemeanor. If you take it, they can not only deny benefits (likely) they can ask for what ever they spent to be reimbursed. (likelihood undetermined)
At least, that is my take. I am sure one of our resident attorneys can correct me if I am mistaken.