IMHO, this is not true anymore. Look, in the 19-20th centuries countries were fighting for the pieces of Africa (WWI, Boer's war, a number of smaller conflicts), because there was some economic value there. Productivity gains made Africa simply economically irrelevant for the Western Society (the evidence is abundant). And once it is economically irrelevant it is irrelevant in all other senses too, there is plenty of tragic processes going on in Africa for years, however, event bleediest heart liberals are not ready to do anything about it beyond cheapest lip service, Africa is simply irrelevant.
This process was masked for a while by geopolitical games originated in the Cold War. Cold War is over and the new reality slowly sinks in. So, the modern world WAS pushing people to the closed proximity, but this is not a case any more.
"Such 'different worlds' must accomodate one another, destroy one another, or one must destroy the other. Accomodation is by far the best choice."
Sure, and the isolation is the most basic form of accomodation between societies. We do not have any accomodations with some societies now and there is no hope that it will suddenly emerge from the outer space. So, let us start from the most basic form of civilized co-existence - establish borders, do not invide their truf and do not allow them to invide ours. Destruction does not smell right for me.
And let us give these morons a chance to grow up without being disturbed by interaction with our world. It did made wonders in the past with other morons, who are now respected members of world community, and I do not see any reason why not to try it again.