At the end of Shmiras HaLashon (Hilchos Rechilus 9:15), the Chofetz Chaim writes that the prohibitions against Lashon Hara and Rechilus do not apply to reshaim and kofrim and that it is, in fact, a mitzvah to mock such persons
UJM,
I would be very careful to research when and with whom these halachos apply.
Eliyahu Hanovi and Yeshayohu Hanovi were punished for speaking disparagingly about Jewish IDOL WORSHIPERS (the real kind) – because “אין הקב”ה רוצה במי שאומר דילטורייא על ישראל”.
(שהש”ר פ”א, ו (א). רש”י ישעי’ ו, ו. ועוד)
The Rambam writes that if such great tzaddikim were punished, how much more so a קל מקלי העולם who dares to condemn so many Yidden as פושעים ורשעים וגויים ופסולי עדות וכופרים בה’ אלהי ישראל.
(אגרת השמד פ”ב)
I would err on the side of speaking positively about Jews.