Bastion/rexec use cases?

[Paul Miller]

Bastion and rexec have been deprecated since Python 2.2, so it seems
we (the Python community) have gotten along well enough without them.
Have these modules not been reimplemented because:

a) There are no valid use cases for them.
b) Doing so would be difficult and prone to breakage as new features
are introduced into the language.
c) Nobody has any idea how to do it.
d) Nobody cares.
e) Guido thinks it's a bad idea.

or, some combination of these?