I asked Warner Losh for clarification but he hasn't gotten back to me yet, so it's unclear if this is meant to apply to just the BE port or both. Unlike the overall industry mood generally, especially from you underannuated whippersnappers who deal with the doublethink of big-endian math in your head but little-endian code in your repos, the BSDs have historically been friendly to big-endian hardware as a means of ensuring code correctness. Indeed, his note acknowledges this. One sticking point seems to be Power ISA's own unique architectural features but I suspect it is due at least as much to the higher cost and poorer availability of the hardware, which has admittedly been thin on the ground lately.
My preference in server operating systems is a BSD-variant and FreeBSD was going to be my own migration plan when I retire my POWER6 running AIX (big-endian, natch), but this news has made me consider OpenBSD/powerpc64 instead. This port is a little suboptimal in that it states it does not presently run under a hypervisor, but it is currently well-supported and specifically tested on Raptor hardware, which is going to be the majority of the ecosystem. Of course, OpenBSD is also a famously opinionated operating system, so there may be a little bit more of a learning curve for me personally, whereas I already have experience with FreeBSD on shared x86_64 hosting and my other BSD systems all run NetBSD (on /mac68k, /cobalt, /macppc, /alpha, /hpcmips and /hpcsh). Another possibility is to try to maintain security patches and fixes on the remnant of FreeBSD 15, though I have such limited time these days I'd prefer not to pour it into another endeavour with an obvious future dead end. I'd dearly love a NetBSD option, but there isn't a NetBSD port that runs on POWER9.
I do think it's a little unfair to cite the user base as being less than "x86 or armv7" when these were extremely common architectures in their day, and a lot of people are probably still running FreeBSD on older examples to get the most money they can out of their hardware. I can't imagine their RISC-V numbers are very high either but no one is saying that should go away, and Power ISA is still very relevant in today's big-iron shops. If and until "low-end" Power11 desktop hardware is available, we'll want all the operating system support we can get too.