This is an old story. Howard Stern asked Paul about this on his show, and from what I recall, Paul said while he thought the Vietnam War was bad, it was really John who was the political or activist Beatle.
I'm not trying to sound biased towards Paul, but in all fairness I've yet to see a direct quote from Paul where he actually says, "I was the activist, I politicized the Beatles, I was more political than John" or whatever. If anyone has seen a direct quote IN context, please post it here.
Here, he's just saying that he talked about the Vietnam War with someone and told the Beatles about it in the end. That's it. I've seen these articles repeatedly and I get the feeling that the writers just twist Paul's words to make them sound worse than they really are.