Hmm
I'm someone who seems to allow my children a lot more freedom / lets them take more risk than others. Spend a lot of time with a secret
while my kids are eg up a tree and everyone else is saying nooooo ethelbert it's too dangerous stoppit and come down.
However I think this is a bad idea for lots of reasons.
All guidance seems to say 5, as under that they won't definitely understand. That seems like quite straightforward guidance and while families might choose to ignore for a school to do so seems odd.
Many reception children are under 5, some have only just turned 4. Both mine had late summer birthdays and so were just a bit over 4 at this time of year. There is a world of difference between that and over 5.
They haven't said what the ratio will be. Have they asked for volunteers to help out? If not then you're looking at a handful of adults for 30 children or similar. Doesn't seem like enough people.
It seems unreasonable for a school to set an activity for a class which by definition some children should not engage in. And so either the young ones / ones who are not so grown up will get left out, or their parents will say OK and they will join in with something that they shouldn't actually be doing.
Why not wait til year one when at least they are all over 5.
Or just say it's for age 5 and up irrespective of class, and have the little ones do some other fun activity.
Anyway that's my thoughts 