There is an inconsistency in the members who can be selected to receive emails for an event and those who can be selected for Event registration type. For emails you permit one to select a Saved search. That is not true for the Event registration type. Since it would seem likely that whoever is selected to receive emails for the event would very likely be those who could respond to the Event registration type, that one should be able to select a Saved search for identify the members who are to be able to use the Event registration type.