I cannot comment on this patch, I just want to state that this
functionality can also be achieved with (id:87sk90ragj.fsf@jhu.edu)
"add functionality in notmuch search mode to add or remove tags by region"
and (id:1266408746-28549-1-git-send-email-Sebastian@SSpaeth.de)
"bind 'd' to new function notmuch-search-delete-thread-or-region"

I think that "add functionality in notmuch search mode to add or remove
tags by region" might be wanted functionality anyway.

Sebastian