Outrage: How to respond?

Nothing wrong with it in my opinion.

The school my kids go to do exactly the same. Its a simple choice, let your kid cycle and enjoy the exercise and fresh air whilst wearing a helmet or pack them up in your car and cause complete mayhem whilst you drop them off at the gates because so many other parents do the same there's no room to park.

My childs school used to send out a letter every term stating that only children who wore helmets were alowed to ride to school. Why on earth the headteacher thought she had the right to dictate this, I'm not sure.
I eventually got into quite a debate with the headteacher about this, gave lots links to the relevant research etc.
Headteacher never admitted she was wrong, but did stop sending the letter.

Schools are in a very difficult position nowadays - what would have, in the past, been seen as an unfortunate accident and put down as a life experience can now be used as an excuse to sue.
Using a legal term , schools have to cover their arses because they can (and do) get sued by greedy morons for any old nonsense.
Schools are screwed by insurance companies just like the rest of us (money that could be better spent on resources) and whilst in principle i find this letter very annoying one has to look at it from the schools point of view.
Its little consolation but at least they are giving you the option for your kid to come without a helmet - some schools wont let kids come at all.
I suppose you could make a moral stand and kick off about it - i would have a good old moan to one or more of the governors about it if i were you.

It is one thing for adults to consent to and choose wearing a helmet or not, but children don't give informed consent. And parents have never had it all their own way in child raising matters, society has always interfered and quite right too. So Sportive rules apply, play by the rules or don't play at all, but feel free to write them a strongly worded letter.

Its very good of them to accept full liability for kids cycling to school with a helmet on. I don't think that is what they are really saying but by explicitly denying liability for those without helmets they are in effect accepting it for those that do. Given the actual statistics for helmets that is a very stupid move on their part. It might be worth mentioning that to them.

Looks fairly reasonable to me but if they can't guarantee the security of the children's bikes / scooters then it makes me wonder how secure it really is...

Prob just a silly insurance insistent clause though.

I don't see the issue with it.
Encouragement to get more kids cycling/be active.

Chances are for the majority of the instances of how kids come off bikes (ignoring getting hit by a car) it's actually within the range of what a helmet is effective for.

What's wrong with that? Seems legit.

It's pretty obvious what the headline is:

"Boy, 10, dies cycling to school [with no helmet]"

Will more kids die from being obese than from cycling related incidents?

Up to you.