That’s pretty much the issue we are discussing above still. The general statement of the problem is that software changes and the format of data they use also changes in incompatible ways. That incompatibility may sometimes be observed going forward, when version N+1 doesn’t understand the data of version N, but it’s more frequently observed when going backwards, when version N doesn’t understand the data of version N+1, because it’s easy to do a migration forwards, but harder to it backwards or introduce completely new ideas while preserving a limited understanding for the old.
So, even if apparmor_parser knows what it supports today, at some point the apparmor profile will evolve, and the old tooling won’t support the new version of the profile anymore. If the snap holding the tooling is reverted into an old version, we need to be able to offer it a format that it can understand. That same problem may happen and will eventually happen with every external dependency that we work with (apparmor, seccomp, udev, etc).