What most people miss -- I was a medical case manager, and the reality is that those who chose to not to wear helmets, who unfortunately end up with head injuries, cost us all. Rarely does medical insurance cover all rehab, which can last for many years. Never does insurance provide "custodial care" that most head injury victims require, sometimes for many years.
We all, through public assistance, pay for this. It's not a simple "right to ride without a helmet" argument.
I assume by rehab, you're talking about Traumatic Brain Injury rather than scalp tears? If so, then your expertise ought to have informed you that bicycle helmets make no discernable difference to TBI.
Meanwhile I hope you're wearing your shower-helmet. I don't want to pay for your so-called "right to shower without a helmet".