Anyone serving in the military deserve respect, those injure, tortured, etc., definitely deserve respect. Any question of this legitimacy, especially for political purposes is wrong. That said, basing your career on and promoting yourself because of this is, well can be, over the top, unnecessary, and just wrong. Whether McCain has or not is open to discussion. Carson and Trump are wrong in questioning or diminishing McCain’s service. How to challenge him politically when he wraps himself in the flag is a challenge so I give pass to everyone on this topic.
If I understand the statements correctly, neither are questioning/diminishing his ‘service’. They are however questioning(diminishing?) his status as ‘hero’....