Denial of Communion is not Excommunication
What to say about this?
(1) Don't assume the reports are accurate; this information was doubtless subject to many permutations before reaching the West. (2) I would need considerable convincing that specific political activities are ever "a sacred duty", let alone ones whose neglect renders one liable to denial of the Eucharist under 1983 CIC 915. And (3), withholding the Eucharist is not (repeat, NOT) the same thing as excommunication (1983 CIC 1331); and note, I have not seen the bishop claim that it is.
Nigeria is a hugely important African nation, both for the Church and the world, but let's wait for more data before forming any conclusions about this particular Church-State encounter.