We are all human, and we tend to have expectation when you are trying to give the impression of being accurate and creditable.
For example, if you are a kid doing a video trying to fix a tricycle the viewers will say that's very cute, and don't care if you make mistakes, and they still love you. If you wear a lab coat and do things using "scientific method", but end up being pseudo science, then you bet some viewers will be convinced that you are doing the right way and come out with the right conclusions, and then others, being alarmed, try to correct things (which may not be true either) by raising the concerns, and sometimes trash talk the hosts.
IMO PF could handle it better by thanking the correction and post a follow up video using the suggested method, instead of saying "Hey, this is what I have and I'm not an expert, just trying to have some fun" and brush off the concern / anger / complains. It really makes a difference whether you address the issue or just run away from it.
It is a classic case of the branding does not live up to the expectation.
