Bastillion cannot connect to two AIX machines

Affected machines:
- test-osuosl-aix72-ppc64-3 (140.211.9.168)
- test-osuosl-aix72-ppc64-4 (140.211.9.169)

Bastillion is unable to connect to either of them. Noting that my Fedora install by default also cannot connect to them, even with `PubkeyAcceptedKeyTypes +ssh-rsa` set in my `.ssh/config` for the machine

Both machines are at version `7200-02-02-1810`. The other machines which work ok are mostly at 7200-04 so a later version.

Start by reproducing the Bastillion connection failure against test-osuosl-aix72-ppc64-3 and test-osuosl-aix72-ppc64-4, then compare their SSH behavior with the working machines. Check whether the AIX version 7200-02-02-1810 explains the failure despite the reported ssh-rsa setting; done means establishing connections or documenting the required compatibility change.

Written by the indexing model from the issue text.