MY friend that the young lady who was schooling her horse today was riding without a hat, she is a good rider but the school surface is not that good after a lot of rain ,adding to the risk.
if she does it again, maybe, but does she normally ride the horse with out a hat? , whose yard is it on? who is responsible etc.. lots of things to consider,.. if you feel unconfortable, then yes, as long as it doesnt cause any friction in the yard!!
Yes! I would not feel happy about someone taking stupid risks while riding my horse. Even if it was their own silly fault I would be devastated if they sustained serious injuries while riding my animal.