Unbelievable that Airbnb support would claim ”all should be fine…
This is most likely an attempt to scam you. Lots if hosts (mostly new, inexperienced hosts) get these now. The inquiries (because it is typically an inquiry, not a request to book), usually have these things in common:
1) Long term stay
2) No previous reviews, limited profile information
3) Often (but not always) Chinese ”guest”
4) Requesting you to go off platform to communicate (often requesting a video, which you cannot send via the Airbnb chat
You should not decline, but you should reply to the message. Then report the guest to Airbnb - and they will look into it.