The openssh developers supporting outdated systems and software forever also isn't a long term solution. Why should they pay this cost, but not you (or your company)?
If you can keep unsupported hardware in operation, why can't you keep a containerized openssh image around, or maybe a VM image, or ideally a statically linked executable?
Maybe your company can hire an expert in software archival to set this up and maintain it if needed, or an extra developer to maintain an openssh fork that supports your environment.
Expecting other people (who you don't even pay) to support your outdated systems doesn't really make sense.
It seems only fair to me that if someone is insisting that they must connect to ancient systems that they should be expected to use only-slightly ancient software to do so. Or fork it, of course. If the team doesn’t want to be responsible for maintenance you’re welcome to take it on.
