Instead of asking others to shoulder the (enormous) burden of backwards compatibility so that his software may continue to work, I think this person would do we

Instead of asking others to shoulder the (enormous) burden of backwards compatibility so that his software may continue to work, I think this person would do well to ask package maintainers to make sure their package metadata is correct (e.g. it lists which versions of Python are supported), and to adopt containerization-based tools for packaging his software dependencies in a sustainable way. The beauty of Docker (and LXC and other container technologies) is that the Linux kernel ABI becomes your backwards-compatible interface, and the kernel maintainers are willing to shoulder that burden.