But certainly the colonies provided safe haven-with Britain defeated, the Germans could have put a lot of pressure on Britain, threatening to continue to bomb cities unless Britain gave up her colonies, either to Germany or Japan.
Consider, for example, how Germany treated France - that is, Vichy in the south was quasi-autonomous (big grain of salt). Nothing in the French North Africa "colonies." Control of Suez was a bit different.
The Japanese were very different; their POW treatment of the Dutch say, was horrific! And yes, recall Naking. But recall also the treatment of the native peoples of the Belgium Congo under King Leopold.
And, the Brits bombed the Germans cities first.