Ex Mozilla engineer says don't use third-party AV

Claims that third-party AVs make your PC less secure because of poorly-implemented code!

In other words, Browser devs dislike AV devs. Apparently, they make a correlation between incompetence and AV industry but any other product (from a different category) can break your application.
a) They could solve such a problem by blacklisting but they do not want to. => devs that design extensions could be affected
b) They could solve such a problem by whitelisting but they do not want to. => hard to maintain

Who’s to blame? I think it’s a hype triggered by egocentrism.