No one is attacking him personally. It was unbiased opinions of the situation. He is obviously a great athlete, but I will respond to your points as a knowledgeable fan and spectator.
A.) He high fived a few people. It was obviously people he knew (who high fives random people before a race?), which makes no difference. smiling and giving high fives before a race seems a bit unorthodox for someone with an important race ahead of them. I think it is more weird that the other people would reach out for a high five 10 secs before someone is racing. A kind good luck or "let's go" would be more appropriate imo.
B.) It sounds like he is a really nice guy, but I would suggest shaking hands and high fiving BEFORE races will take away from focusing on the race ahead and looked odd which was noticed by a couple people.
c.) In context of the NCAA championships Binghamhamton is a lesser known school. When I saw Van ingen run the sub 4 miles I was like who is Binghamton. When you are in a meet with the biggest colleges in the NCAA Binghamton is very much a lesser known school. Although that is probably irrelevant.
d) He had way more pressure in this race than the others you stated.
Point is, he was the only athlete to smile and give high fives before the race and then he false started. If you believe it had no effect, fine, but other people thought it was a bit odd.