Ok, here is my attempt to code this:

This seem to work for my example from the start of discussion(not tested it much for now).

If you set a 'heay' buffer-predicate like here

(This package provide a way to switch between 'projects',

each project has a list of buffers, it is essential to set a buffer-predicate that

will constrain buffer switching to the current 'project' so it needs to check if a

buffer is a member of the current project list. There may be many buffers from

many projects)

And if you are the user of a package that overuse the with-temp-buffer(like helm

or if you run down the list of candidates of the company-mode) you can notice a

slowdown.

And I just think that this behavior of the kill-buffer is wrong and could be fixed

quite easily and without introducing new functions or breaking user experience.

Maybe I'm wrong.

And I'm not saying that this is a critical bug or somehow urgent, just wanted to

discuss the idea.