McCain was not much of a much at the academy, not much of a much as an officer, not much of a much as a pilot (expensive in aircraft as I recall,) and, as senator, not much of a much would be a major improvement. His behavior as POW was and is honorable (I'll leave the definition of "heroic" to others,) but short of playing the Daddy card, or worse, to opt out, what else was he to do but endure?
I have but one use for the GOP and that is they offer the best, such as it is, chance to exclude Democrats in elections. Neither McCain nor Trump contribute to that. Trump seems to actively defeat that purpose.