Could have been some sort of spy or informant, or could be (and still may be) part of a leftist effort that is not fully revealed.
Something is really off about Kerry, he has gotten away with way too much without being called on it. What made him teflon back then and what makes him teflon now?
Kerry seems to have been protected back in the 70s by Ted Kennedy for whom Kerry worked (at the age of 18 he was working in TK's office), and also by Senator Fulbright.
If you read a bit about Fulbright, it's obvious that he didn't have the best interests of the country at heart, and it's not a stretch to think he was promoting this war protester/VN veteran, who fit perfectly into efforts to stop the war at any cost.
Kerry had 2 powerful protectors, 2 US Senators, that's what it looks like to me.
I guess you're right, he was born into some powerful connections. Still, from his record it is absolutely amazing he got to be a Senator. It is also amazing that his Vietnam-era activities didn't preclude the Democrats from selecting him.