The repealing of helmet laws in QLD is only for designated cycle paths - that does not include the bike lanes that run alongside the road (that always seem to be uselessly full of cars)
So riding your pushy with your kids/dog at the park is fine without a helmet, riding the designated cycle paths around the city and up to redcliffe is fine without a helmet - but - you would need to carry one with you anyway as the cycle paths traverse roads in places, and you need to wear a helmet if you are riding on the road.
Why not just wear a helmet? I don't give a shit about my hair, the stuff grows back... its the stuff inside the skull that doesn't (but it would seem 75% of the population doesn't have anything in there anyway...) and I would rather have some sort of protection for the important bit of my body, regardless of cycle path or no, on the off chance that an errant dog/child/overly engrossed smartphone user suddenly jumped out in front of me and I went OTB (its happened before!!)
As for this inflatable helmet... nice idea, but expensive and useless for certain conditions (riding to work with one of those things around your neck during a QLD summer would be fuuuuunnnnnn...)