Earlier quoted context omitted.
There are multiple islands and archipelagos in the region. Close to Africa/ME: Maldives, Seychelles, Comoros, Mayotte Close to SE Asia: Cocos and Christmas Island Diego Garcia just happened to be forcibly depopulated by the British, so was a convenient choice.
I mean, what current option is equivalent to Diego Garcia? Are any of those options realistic right now?
If Diego Garcia were no longer an option, there would be alternatives. Especially with US levels of lease money.
That said, few of them are quite as remote as Diego Garcia. Which means not quite as easy to secretly fly RQ-180s or whatever the hell is more clandestinely based there.