My understanding of their comment is that they’re talking about getting older Python interpreters to run on more modern OSes, modern enough that they don’t carry the older Python as a system package anymore. Hence, deadsnakes.
That's indeed extremely specific. I'd imagine this pain could be self-inflicted with C-based extensions that were compiled (and can't be recompiled) with structures that don't exist in other versions.
I don't want to imagine what other eldritch horrors await developers working on this application.
I also imagine the scenario you mentioned causing a lock to a patch version. But I see this as just a normal steady state a lot of orgs drift to if not staying on top of version updates
Drop by and send thanks cause he really needs them.