Just good ol' government propaganda.
You can do mental gymnastics to try and make Xebec seem like a bad guy, but in reality he didn't do anything more evil than the SH crew or the average pirate crew.
He beat up Loki? I'd say he just gave him a good lesson, Xebec humbled him while he was still young, Loki's overconfidence would probably lead him to death if he didn't get that lesson.