Why did McCain and Kerry betray their country and the POWs during senate hearings?

Starting at 2:05, one POW talks about how McCain and Kerry actually walked out on his testimony--along with others--so that they won't be forced to look into the missing MIA/POW cases. This is a hearing that McCain alone fought to not have in the first place! They disrespected the vets and American democracy! Shouldn't they both be forced to resign for being traitors?