I haven't worked in a neuro ward but have been to a few arrests in one when I was a CCU nurse. Slightly irresponsible for riding a dirt jump sans helmet, yep, end of the world call the press and child protection, nah.
The jumps are dirt, not a rocky down hill track. The worst thing you can do with your head is hit something that is very hard. I think you'd be at more risk going out drinking in an urban environment with concrete and steel everywhere than mucking round on your new bike in front of your toddler.
I am sure all the shocked burners have never been backpacking and ridden a motorbike in a third world country helmetless, or done a burnout when on their P's back in the 80s etc etc.