sacking mecca, and raiding muslims.
A yes but they came up with an excuse to justify it.
This pod is post 1600s so the ottomans are absolutely legitimate and powerful enough to get away with it.
Ali didn't punish the people who killed the last caliph, the umayyads killed Muhammad grandsons, the abbasids red wedding the umayyad clan you are overplaying how legitimacy losing waging war against muslims is, the greatest caliphates have all done terrible stuff and they are still legitimate and by the time of the ottomans waging war on fellow muslims was fine, even if the religion says no everyone did it.