Host cancelling reservation

Hi all

Ive had an unfortunate circumstance where a host has messaged me saying that he needs to cancel my reservation however he is asking me to cancel it on my end then i will receive a 100% refund.

I am hesitant to do this as im worried it wont give me a refund if i do it on my end. He is refusing to do it on his end saying he cant but i am skeptical of this.

Ive advised him on the in app messager that ill need to go to the airbnb people for mediation

Am i acting unreasonably or am i doing the right thing? I havent had much experience with this