Hey Matt, I got a couple things that might point you in the right direction, but unfortunately I didn’t have the time to fully solve this.
As far as I can tell field.metadata.picklistEntries is actually only used on UI only fields. This might not be 100% accurate, but without doing an extensive read through the source code, this is the behavior that is presented.
That being said, your snippet should work on a UI only field. Maybe you can use a UI only field and leverage some model actions to accomplish what you are trying to do.
