That seems a bit at-odds with the advice to "be nice to them", does it not?
Or perhaps the ideals fail and you just need to bare your teeth at them. But return to civility; no reason to senselessly burn bridges. (What if they're just horrible? Then leave. What if you just can't walk away quietly? Well, just try not to burn bridges as a first resort, at least not while you're standing on it ;)
To me it means to try not to act out of malice, hurt, or anger towards others, even when they seem to be acting that way towards you. You can calmly and rationally explain your position, and hold firm, while trying to avoid negative emotions. Easier said than done, but it can be incredibly powerful.