I use whatever is provided by the package manager. Even on Debian, pkg-config is a dummy package that redirects to pkgconf.
Their stance doesn't seem particularly "aggressive" in context because they call out "passive-aggressive people who try to argue with us". Seems they probably had some people who opened numerous issues reporting closely related problems that they were told multiple times are not bugs. It would be like... what if someone opened multiple issues for Geany complaining that it doesn't support various Qt6 features despite being told multiple times that they aren't bugs? Eventually, those complaints could be considered intentionally disruptive, and people who "insist" on continuing need to be cut off.