There are people out there with short-range, wireless pacemakers with no security. Most just provide information you’d expect but some of them are also defibrillators (they can kill). As far as I know none have been harmed in an hacked attack but a hacked brain implant brings to mind more than just killing the owner. We may have an interest as a society in making this illegal because it’s not worth the gamble to us for people’s actions to be hijacked remotely.
I highly doubt that someone disabled enough to need implants like this is capable of doing damage to anyone but themselves. Like if you’re interested in protecting them, sure I’ll accept that. But the idea that society needs to protect itself from this is silly.
I don’t understand how one could think brain implants is a totally safe invention for a society. Did you consider more possibilities than just manipulating people into to physically attacking others?