This makes more sense now. I'd submit using their unsolicited evidence.
USCIS' does state:
If you forget to send in supporting documentation with your benefit request package, please do not submit them in a separate package to a USCIS lockbox. Please retain the supporting documents so they can be submitted later, if requested by USCIS.
That said, there's 100% chance you'll receive an RFE, or NOID. There's no such thing that bona fide marriage evidence is not required.