Read these claims with a pretty big asterisk. Implementation quality of HBSD features is often poor or very poor. https://www.fabiankeil.de/gehacktes/hardenedbsd/ is just one example. Specifically some of the changes made to "harden" the system are pretty dubious and introduce new bugs, possibly security relevant, that did not previously exist. No one runs or pen tests HBSD. It's even more niche than OpenBSD.