Disabled item in Custom Field?

We have a Select Multiple type custom field which lists all of our customers’
company names. Every now and then a customer either changes its name or does
something that affects what we call it in our list. Sometimes this simply
requires adding the new name, updating all the tickets labeled with the old one
by labeling them with the new name and then deleting the old one. However,
sometimes we need to keep the tickets created under the old name as they are
while all new tickets get the new name.

This leads me to my question. Or more accurately, a feature request. It would
be nice to maintain items in a list such as the one I described but be able to
mark them as disabled so they don’t show up when selecting from the list.
Perhaps in doing so, on the Query Builder page a separate list can be built up
from the disabled items so that they are still searchable.

Is this feasible?