Is uttering abusive phrases such as "Enough of your terrorism, man" or "You, people of misguidance and backwardness" considered a mockery on the part of the speaker, and thus unlawful?

There is no harm in using phrases of sarcasm or praise for someone undeserving, as a form of mockery of the speaker or the intended person. An example of this is the Almighty's saying: {Taste! Verily, you are the mighty, the noble!}, which was revealed in sarcasm of Abu Jahl, who claimed might and nobility.