I don't know Hungary well enough to have an opinion. But I don't see that a country must desire to make itself a racially mixed entity.
The US isn't a shining example of how mass-scale racial mixing can work to produce a happy country. I tend to be interested in what works, and not so much what one might think is right or ideal.
Orban may say - there's another country we don't want to model ourself on. I don't know.
But personally, I rather like the gradual mixing in of people with varied ethnicities. The key point is gradual, because the history of tension in these things when they are large scale is something of a theme in human history. It doesn't always end well, whatever we might desire to be true.