You don't want to sign an economic deal that is itself a security guarantee, then fine. Be up front about that, say you want to come to talk, don't lead POTUS on about it, don't dress like a bum and make demands in public while sitting in the WH.
But, Z is in a tough spot and I think that we need to be open for a re-engagement before we cut Ukraine loose and let them fend for themselves with help from whomever in europe wants to help.
Z man needs to check himself, re-think his approach, buy a coat and tie with some of the money that he has put in his pocket courtesy of the US Taxpayers, and fly is his ass back over here and try again.