Sage has gained a new meaning and now basically means "fuck you". Anytime a word changes meaning, it is futile to fight against it, because it NEVER works. Ever. Even if every chan owner made it against the rules to use sage in hostility on threat of permaban, it would still be used that way.

If you wish to have the function of sage without the insult, you need to create a "new" fuction. Call it "nobump" or "pnb" (polite no bump) or something. Keep in mind, as long as people see an underlined and color changed name, they will think it's a sage. A function to not bump a thread should not be stuffed into the email field anyways, it needs a check box.