Can't set moderation action for nonmember from held message modal

When a message from a non-member is held, Mailman creates a nonmember record for that user.

The moderation modal offers a way to set the moderation action for the message sender:

This is great! But it doesn't work unless the sender is a member. It doesn't work when the sender is a nonmember, even though there is a nonmember record associated with that email address. To be specific, it says something like "setting moderation action failed because foo@example.com is not a list member" (not verbatim).

This would be useful for the scenario where someone is sending to the list from an alternate address and you want to set that address to always accept, for instance, without actually adding the address as a member.

I imagine it would be useful in lots of other scenarios too!

Thoughts? Thanks!