What we say off-the-cuff in unguarded moments is more likely to reflect what is really in our heart, IMHO. I think that we have to consider Kerry as a potentially unhinged, unstable man who harbors a deeper level of ill-will toward the president that we might have imagined. This is the man who was present at a meeting in which political assasinations was discussed. He did not disassociate himself from that group. This says to me that there's a substantial likelihood that this man has not yet grown up and is still a danger.
That certainly is a possibility.