If it is the case (actually, now even the govt high position people are not allowed), why he left illegally, as I understand. Or perhaps, because he would not be allowed out into Russia, even for his kids?
However, the Russians did let him in, did not hinder to approch his kids, did they? And did not hinder him to take them out of Russia, did they? I guess he thanked them a lot - you are welcome...