The rulebook says the duration of half-time must be specified in competition rules and can be altered if the referee allows it.
"Players are entitled to an interval at half-time, not exceeding 15 minutes; a short drinks break (which should not exceed one minute) is permitted at the interval of half-time in extra time. Competition rules must state the duration of the half-time interval and it may be altered only with the referee’s permission."
You could argue that that this rule allows referees to extend the half-time break.
What would be the purpose of the clause "not exceeding 15 minutes" then? The rule is clear: the competition can choose an inverval duration between 0-15 minutes, the referee can alter it inside that range (I've only ever seen it extended beyond that span for unplanned force majeure reasons like a storm).
In any case it's clear that the WC referee had no role in the scheduling of those half-time antics.
"Players are entitled to an interval at half-time, not exceeding 15 minutes; a short drinks break (which should not exceed one minute) is permitted at the interval of half-time in extra time. Competition rules must state the duration of the half-time interval and it may be altered only with the referee’s permission."
You could argue that that this rule allows referees to extend the half-time break.