How is J Sidney McCain's experience in Vietnam relevant to his qualifications for the office of president? If it is relevant at all, it is because it shows that he hasn't learned a damned thing in 40 odd years. You'd think that having been one of the saps screwed up in the debacle in Vietnam would make him a little more cautious about such debacles and throwing away young lives in them. The inability to learn from such a significant experience is not something that we should be looking for in a president.
Secondly, J Sidney McCain seems to be hoping that his service as a captive will give him a free pass on criticism. We're supposed to overlook that he has been nothing but a douchebag since the day he was released because he was an EPW. He knows that Democrats don't have it in them to trot out some lying sacks of shit to say that J Sidney was actually a traitor who sodomized his fellow captives. Some right wing nut jobs, who kind of hate him, might do it, but he's banking on their hating black people more.
Thirdly, inept fighter pilot is only one small item on his resume, and you have to look at his entire lifetime of parasitism on the US government to appreciate where his service fits in.