This is extremely late, but for another reason to have Kidston alive is that upon death they have a time limit until the body and all related body parts disappear. A time limit that is unknown, as there's no telling just how many hours they have until that happens (my character will say it depends on the individual if his opinion is solicited) and how exactly long they'll need the use of Kidston's wings for.

Would that be more convincing for Loki?