As long as Linux Mint developers are not doing that how it helps you? you don't trust Canonical binaries but you trust the deb binaries, you could be honest and claim that you don't like snap but you still trust the deb binaries.
The point is that you can audit without having to depend on a third party. Nobody's claiming audits are free or that they're assumed. The point is that you have the option to choose to trust as much or as little of the build chain, from the compiler to the target code to the artifacts.
- Mint uses Ubuntu repositories
- Canonical pushes the changes they want into this repos, this changes are probably done by scripts that build source code on Canonical servers.
- the Ubuntu repos also contain binary blobs
- when a Mint user does an update he gets the binary directly from Canonical servers, there is no Mint dev or Mint script that does any check to see if for example the evil Canonical modified the NVIDIA driver and added even more evil in it then already is
Now explain to me if all the above is true why would someone that does not trust Canonical would use Mint? There is no safety checks to prevent evil Canonical people do evil things.
My conclusion is if you don't trust Canonical don't use Mint. Maybe Mint is working on addressing this and soon we will see an PR campaign that announces they are finally able to self host but until then I would stop the hypocrisy about not trusting Canonical. (Btw there are many smaller distros that can host their own repos, not sure why Mint is not doing it)