Aubergine, EvansandAnna'smom, schools are not historically good arbiters of morality. Sometimes they get things wrong. I don't think I would ever in a million years use the school environment to justify why something is right or wrong- I'd look at the grownup situation instead.
And shame on your school for not responding appropriately to sexual harrassment. I suspect the details and long and painful, but in general I would say that a legal approach was better than if you had hurt your harrasser and/or school administrators.
I'm not sure extrapolating to a grownup situation works either though. We make rules for 4 YOs that will not apply to grownups all the time. "You must sit in your carseat" is a simplistic example. Later that might morph into "booster seat in my car, regular seat in Dad's car" (because fit/safety considerations are different), to "back seat in my car, front seat OK in grandpa's truck" and finally to "wear a seatbelt". Things change as children grow older. I am comfortable saying "no hitting in our house" to children who are 4 and 6 without implying that I am also telling an adult not to defend themselves in the case of an attack.