seems perfectly sensible to restrict cert 18 but would have thought cert 15 are acceptable.
we don't know what the complaint was or if the measures taken by the cinema address it or go too far.
if there was a scenario when an infant was in a regular screening, then I would completely understand the complaint.
if the complaint was from someone who attended a parent screening, then - well, I guess it depends what was on!
if the complaint was from someone who has not involvement or experience then the cinema surely wouldn't have taken measures based on it