Also not sure if same on classic but there is a nonhuman head rule aswell, so maybe thats also why cause its not really human like just character/bighead yellow/red..

Heads like these are sometimes tricky to decide whether it should be accepted or not as some rules clash with others i.e some allow earings but not a headband etc even though rules would state no hats etc

Personally Ithink anything within reason should be allowed (apart from having a hat on etc-something that would make player not want to buy other hats and apart from rude stuff/images /the ovious stuff that you wouldnt exspect being rejected anyway) but hey rules are rules..