The rule here is being absent for all meetings during a six month period (irrespective of how many or few meetings missed), without giving a reason accepted by the council will result in the councillor's seat falling vacant. The notice of a meeting is actually a summons requiring each member to attend. The Chair has no capacity to add to that.
The commonsense approach might be for the council to approve this member's absence in advance so as not to trigger the six month rule.