Hello @Éimhín-And-Jonny0,
I'd contact support to register the issue.
As you have instant book set guests should be able to book only if they meet your requirements. If they don't meet them they can still send reservation requests.
I have instant book set and recently received requests from guests with no profile photo. I messaged support asking how this was possible and they just said "we passed your question to the team".
I responded to the guest by asking them to upload a photo before approving them.
With a confirmed booking from someone who doesn't meet requirements, I'd ask them to upload a profile photo and to go through the verification process. I'd contact support about the issue in any case and, if the guest doesn't comply within 20 hours, ask that the reservation be cancelled.
Steve.