Future Guest is ghosting me; AirBnB unhelpful

I have a guest who booked in November (3 months from now). There was a lot of original communication from the guest (all positive) when we initially finalized the booking. Then suddenly the guest has gone silent. I've sent them several follow up / reminder messages over the past month through AirBnB - with no response from the guest. They have not signed our rental agreement, which is why I've been trying to get in touch with them. I don't normally do this, but I texted them as well since I was getting no response from them on AirBnB...and still no response.

I simply cannot get in touch with this guest, and I do want to enforce the rental agreement so this is important to me.

I escalated this to AirBnB support to see if they'd be willing to attempt to contact the guest, and they basically told me "no" (see below). Surprisingly they also told me that they will enforcing a rental agreement an that the booking is still "valid" even if they do not sign my rental agreement. Does this mean that if the guest refuses to sign, I must still go through with the booking? I'm trying to avoid that scenario so any advice would be appreciated.

For context, I've booked 48 guest so far (all 5 stars) and I've never had this situation happen before. A first for me