unmanage interfaces indefinitely rather than delete them

I'm working on scripts to automate adding devices and resources.   It appears that I can't selectively add Resources after a list resource via API, only import the whole thing.  So I want to go back after doing the list resources and unmanage the interfaces I'm not interested in.  I'm looking at Orion.NPM.Interfaces and see this:

Problem is, it appears to want to force me to supply an unmanage and remanage time.  My preference is to unmanage it and leave the times blank.  I SUPPOSE I could give it a time 100 years in the future, but I'd rather not.   If I simply don't inlcude those fields, it borks.  If I include the fields and leave them blank, it borks differently.   Suggestions on how I want to approach it?