I believe there are some groups of people in any giving field that are set in there ways.They want to hear nothing that might rock there ship.
I have no doubt you are right. Simply dismissing any new idea out of hand will result in a person being right 99% of the time and I bet this kind of behaviour is rife in the scientific community.
Proponents of new ideas who are not well known are in an awkward position where they have to provide a exceptional level of evidence to even be noticed by their peers. In this case the guy even decided to swallow some of the bacteria to support his idea. Once he provided a situation where some people went "hmm that's funny" then his idea stood out amonst the hundreds of new ideas out there and someone looked into it more.
But yea I think it is quite normal for valid new ideas to take decades to be acceped. It's not desirable but what can they do to change it? I don't know