The only reason infosec.exchange isn't defederated is from grapheneos.social is because it's too big to fail.
infosec.exchange has very consistently failed to address rampant libel and harassment directed towards our team from their instance.
At one point, the admin of the instance publicly posted we'd reported harassment with details and asked for feedback which acted as a rallying cry for people engaged in these attacks. None was addressed. We stopped filing reports of harassment to them.