Partisanship and political opinions aside, you have to have the utmost respect for what John McCain sacrificed for his country.
After less than a 1 year of imprisonment, his father was named commander of all U.S. forces in the Vietnam theater. The North Vietnamese offered him release because of this. He refused unless everyone captured before was released first. He denied his own freedom and spent another 4 1/2 years as a POW (5 1/2 years total as a POW).
Technically John McCain was the only POW in the Hanoi Hilton there 'voluntarily'. It's your actions that define who you are as a person. I wouldn't even deserve the honor of carrying the mans briefcase.
The POW section is worth a read:
https://en.wikipedia.org/wiki/John_McCain