from my understanding, and I may be wrong about this... but RTU is like NOJ in the fact that while its held at universal, ticketed by them, and staffed by them it is actually in reality a private event where the organizers have worked out a deal with the park to hold it there etc, and in return universal gets a percentage and a handy tax break for a charitable contribution. Its the organizers who handle what dates the event is held and keep it during those days.
and in that case.... they should be aware its during this time that universal prepares for HHN, and should take responsibility for the knowledge that props maybe out at that time. And, if they find those things offensive, they should find a new time of year to hold the event.
of course that would involve people taking personal responsibility AND not expecting others to cater to their beliefs like they are the only ones in the world.