Much like 'notify briefly' allows you to add an OOC message of why, I think 'invite reject' ought to, also.
Since invite can be used for spoopy dealings, but not end in kidnapping or death, etc, we can and will get invites from cloaked/masked people where we may not actually know who they are, and can't offer an explanation of why it is rejected via tell or other means. (i.e. Character unfamiliar with the room, about to log off, whatever reason it might be.)
I find this important so the person on the other side can know if the invites are still welcome, and the rejection is not because of the spoopy nature. So they can try again and not feel put-off, like the person will never accept.