Why is Britain in scare quotes?
I think the Watchtower has a problem calling our country by its proper political name - "United Kingdom" as that would undermine their religious claims on that terminology
and so prefers the strictly geographical term "Britain" instead, although Great Britain would be technically more accurate in that case.
Including Northern Ireland in with Ireland makes logistical sense, but possibly speaks more to pro-republican sympathies common on the East Coast of the USA