My mother always said "let them have their own accident somewhere else."

If someone is driving unsafely around me, I absolutely feel offense and the desire to punish them in some way, but it seems best not to do so. Unsafe drivers probably won't learn anything good from other drivers no matter how the other drivers respond. If you try to create consequences, the other driver may well escalate - for example, as you described, passing on the shoulder and creating an unsafe situation for others; but also possibly by taking issue with you personally and acting to endanger you directly through various methods.

So in summary, if someone is driving unsafely around me, my goal very quickly becomes getting the lack of safety away from my passengers and myself as soon as possible.

You don't know why someone is speeding, and it's not your job to enforce traffic laws. There was a story I remember reading a while back of someone's friend having a chainsaw accident, and them watching their friend bleed out in their car because some dumb piece of shit figured they'd play traffic cop and blocked them in traffic. If you see someone driving aggressively, just assume they're driving that way because they're about to shit their pants, and let them go on their merry way. Report them if you want, but don't endanger yourself and others trying to be a "hero"