Ann: Extension to Voluntary Suspension, page-272

IF they are signed up to the JV agreement, which they must be, then the rules for arbitration are laid out in there.
IF AVZ are not signed up to the JV agreement....almost impossible to believe....then they could probably ignore it.
Given there has been an arbitration request and AVZ have announced it without saying they are not party to the JV agreement thereby can't actually be taken to arbitration one can only assume they can be and are trying to fight it off.
IF anyone has a copy of the JV agreement it would make interesting reading IMO.