I’m confused why they can’t just write a sandbox profile that does the equivalent
They just got burned by the documented usage of sandbox_init() going away (which didn’t even get a mention in the release notes), I can understand why they’d be unexcited about moving to a different deprecated/undocumented API.
So I think it would be up to the team that ports it to Apple, so I think the "Apple Team" is the ones who would worry about sandboxing.
There are a couple of people who have done significant work on OpenBSD's ssh (eg Markus, Theo) and various OpenBSD folks who add a feature or fix a bug and move on.
There is one person who currently works exclusively on -Portable (Tim Rice, who is still around although not very active these days) and at least one other in the past (Andre Lucas, who wrote the multi-platform login recording code). You can see the current set here: https://github.com/openssh/openssh-portable/blob/master/.git...