I suspect Apple considers developers ignoring a five(?) year notice period that 32 bit compatibility will be dropped a sign that the publisher has already abandoned their software.
Expecting old software to be backwards compatible forever is unrealistic. Even modern 64-bit Windows doesn't support 16 bit applications, and the only reason this isn't a problem is because of how long ago they were of any importance.
Old software still lives on in emulation and old hardware. If a developer doesn't feel the need to keep it updated for new hardware, it can join the outdated hardware it was made for in the archive.