Perhaps, for a short time, the EC could meet informally in private to discuss matters on the agenda of each up-coming meeting. That way, EC members could have the civilised, unrushed, uninterrupted exchange and testing of ideas that is necessary for good decision making. Then, as is proper, the actual decisions could be made and minuted at the notified meeting in quite rapid succession without the risk that some useful contribution from an EC member would go unheard by the other EC members.
There might be some spluttering indignation from your disruptive owner as you race through the agenda at the formal meeting but at least you would get the business of the EC done. It might take a while for the disruptive owner to cotton on and even then, what could they do? There is no reason why EC members can’t talk informally among themselves when not having an EC meeting. Then, at the actual meeting, they can find themselves surprisingly quickly in unanimity with the first thing said on a matter, quickly resolve to make that a decision and move to the next agenda item.