If you guarantee that your binary has source, it has source. Guaranteed.
If users only want binaries that guarantee they have source, they can insist on only downloading/acquiring binaries from people that guarantee they provide source.
If you as a developer want to ensure that users of your code or modifications thereof will have access to that source code (end user which often includes the original developer himself) permissive licences does NOT _guarantee_ that.
Only way to guarantee that is to make it a condition for using the code in question, which is exactly what GPL does.
Do we really need to continue this dance of yours?
No it's not, do you know what a 'guarantee' is? Unless the code in question comes with that as a _condition_ there is no _guarantee_.