Apparently, this FreeBSD port requires the PS3 have a tool called "petitboot" installed; the "petitboot" installation process seems to use the PS3's traditional "OtherOS" support (what you refer to as "Linux support"). So a PS3 whose firmware prohibits it from booting Linux won't be able to run FreeBSD either.

Now that all the signing keys are leaked, I'll be interested to see how long it takes for universal installers to appear that work even on PS3s that don't support "OtherOS".