Meanwhile, the OS X Leopard OpenSSH 10.3p1 issues related to PAM (which I think was heavily reworked relatively recently) seems as if they may be able to be worked around by disabling PAM and passphrase authentication and just using SSH keys?

https://trac.macports.org/ticket/73757#comment:8

I still haven't dredged up any of my OS X Leopard vintage laptops to recreate let alone remediate these issues, though I am heartened that maybe someone figured out a workaround.

(Honestly, having contended with various issues related to PAM and passphrases: I kinda think using public/private SSH keypairs is maybe, a saner way to go anyway?)