According to Tameichi Haras Wikipedia entry he was not personally involved in the sinking of PT-109 and would have had no first hand knowledge of the incident. He was certainly in no position to know JFK as a commander or naval officer.
Towards the end of the War, he did, however, train young men to fight dressed as women and children, so he would know about “somewhat less than heroic”.
Per his book, he was on one of the destroyers accompanying the Amagiri, and witnessed PT-109 motoring right into the Amagiri’s path. He also wrote his memoirs in the late 1950s, before Kennedy was a major figure, so he had no axe to grind about the incident.