One person's 'tone policing' is another person's 'advice on how to most effectivly get your point across'.

It's not helpful advice. The post above attacks the author's writing credibility due solely to its emotional tenor. That's essentially an ad hominem.

> he should create a second, more black-and-white version that comes off as more credible and is less easily dismissed.

Its absolutely not ad hom. It's saying that the writing style chosen isn't optimal if the author wants to be seen as credible. It says nothing about the author, his credentials, or expertise and does not attack him as a person.