Honestly haven't looked at his comment before you mentioned it, but upon having read it you're incorrect. My argument is that Southern Africans benefitted from colonialism based on observable metrics, whereas the only benefit derived from third-world immigration to the aforementioned European countries is by means of population growth.
Then again with the onset of automation and advancement of robotics, which will lead to less people being employed and less of a requirement for population replacement to sustain the economy, one could argue that even that is no longer a benefit, which is probably why the UK is starting to experiment with methods to avoid this problem.
To imply my argument applies to Corelli's proves you haven't read it, how exactly did modern immigration from the Middle East and impoverished Africa advance European societies, and how is it an overall benefit? Once again the only metric by which one would judge this to be a case would be population growth, which I've already pointed out is no longer the case. All other metrics, crime, violence, rape, murder, religious violence and ethnic tensions are up as a result. When they arrived in Europe, didn't they do so precisely because European societies were more advanced? Are you implying that Europeans settled in Southern Africa because Southern Africa was more advanced?
Either you're completely incorrect, or you haven't properly explained your position.