is it safe to wrap a rvk fan in cling film and put in styrene filled box

ive seen a diy solution for reducing the sound of an inline fan by wraping it in cling film and placing in a cradboard box filled with expanded styrene,is this safe,does the fan not get hot?

I think the fan would vent all the heat it generates so I wouldn't be worried about it, but I don't see the point in cling film unless the styrene could get in some how?