Cool!
Guessing you can probably do something similar for automation items. It seems an action for limiting a deletion of selected points to time selection would be a nice utility to have, but I guess I have not really lost any sleep over it thus far.
It probably makes two undo points for the two calls to mainoncommand? I'll try it later with a undoblock to reduce it to one and edit this post. Alternatively you can use namedcommandlookup on a custom action that you make normally.