Before you start collaborating with someone so recklessly, first find out whether or not they use "PhD" as part of their name in their email account. Life is too short to spend it working with people who are so attached to their "PhD"...
That’s a fair point. Regardless of the hurdles, we can try to avoid using “I have a PhD” as a premise in an argument, because then we’d place even more people at a rhetorical disadvantage. I could’ve been clearer about the target of my criticism.