What does putin mean by allowing this?

It's not about the caste. It's the kind of diaspora a country has already established, and the kind of policies they promote. Canada went for the low skill ones. Being a welfare state, they got all the unskilled workers coming in and exploiting their welfare system while providing little value to the economy. This diaspora started flexing their comfortable lives, and all the unskilled people looking for the glamorous lifestyles started coming in. The result? Shit immigration. The US was much more selective with who they let in. They provided the best opportunities in the world: universities, companies, labs, and by making access to them selective they got to keep the best ones. CEOs, doctors, engineers, and especially researchers who have contributed out-proportionately to the past tech boom, the current AI boom and the coming robotics boom. Scandinavian countries prioritized a lot of STEM research so that's the kind of diaspora they are receiving. Germany went for a mix of low-skill healthcare workers, business professionals, and tech workers. Considering Germany was still marketed as a low cost high return country with cheap education, it did get some nefarious diaspora which doesn't integrate very well, but nowhere as bad as Canada. Ireland and the Netherlands are like Germany but without the low-skill aspect and the negatives for the most part. The UK is honestly a mixed bag. They've had a very longstanding exchange of labour with India, so there's all kinds of people. On average though, much better than the Pakistanis there.