I still remember watching this interview with Mikhail Gorbachev in my high school journalism class.  When Tom Brokaw asked Gorbachev about Soviet emigration restrictions, the Soviet dictator self-righteously replied

What they’re [the West] organizing is a brain drain.  And of course, we’re protecting ourselves.  That’s Number One.  Then, secondly, we will never accept a condition when the people are being exhorted from outside to leave their country.

This “brain drain” rationale was pervasive behind the Iron Curtain.  From Alan Dowty’s Closed Borders: The Contemporary Assault on Freedom of Movement (1989):

Marxist states typically place great stress on rapid
modernization and development, and achieving those goals depends on the
services of highly trained professionals. 
But few groups feel more threatened by Marxist governments than this
one.  From a position of privilege and
high reward, they are reduced to salaried servants of the state.  The Marxist commitment to egalitarianism
undermines the incentive structure that professionals thrive on – and which is
usually available in neighboring lands.

Thus, to prevent a brain drain, an open emigration policy
might force a state to readjust its wage structure, at a cost to other economic
priorities, not to mention ideology. 
This was the conclusion, for example, of Zsuzsa Ferge, a Hungarian sociologist
who studied the economic impact of her own country’s relatively liberal
emigration policies: as Hungary began to compete with the Western labor market,
it was forced to increase rewards to professionals.  Representatives of Romania and Bulgaria, on
the other hand, argue that they cannot afford to match Western salaries, and
that, without a restrictive emigration policy, they “would become like Africa.”
[from Dowty’s personal interviews with diplomatic representatives of Romania
and Hungary]

To be sure, Communist fretting about “brain drain” seems hypocritical.  If they really cared about national well-being, their first logical step would be to end their brutal dictatorships.  But none of this shows that the Communist arguments against free emigration were false.  Allowing free emigration really could be worse for national well-being – especially if you stop counting your citizens’ well-being the moment they jump ship to another country.

Now suppose you subscribe to the political philosophy of citizenism: You think that governments should maximize the well-being of their citizens, with little regard for non-citizens.  Is there any principled reason to reject emigration restrictions?  The citizenist could say, “I favor putting citizens’ interests ahead of foreigners’ interests, but not some citizens’ interests ahead of other citizens’ interests.”  But immigration restrictions clearly do the latter.  Some citizens greatly benefit from doing business with foreigners; immigration law still tells them, “Tough luck.”  In the real world, every citizenist has to make trade-offs between the welfare of different kinds of citizens.  
Question: If citizenism justifies immigration restrictions, why not emigration restrictions?  Or to put it more provocatively, tell me: If Gorbachev supported emigration restrictions after a sincere analysis revealed they advanced for the overall interests of the Soviet people at the expense of the high-skilled minority, is there any reason Gorbachev shouldn’t be a citizenist icon for standing up to rootless cosmopolitanism

P.S. I am well-aware that leading citizenist philosopher Steve Sailer admits exceptions to his citizenist rule.  But to the best of my knowledge, he has never enumerated the main exceptions or even suggested general guidelines for making such exceptions.  What we do know is that, in his eyes, even tighter immigration restrictions than already exist are morally unobjectionable.  Status quo bias aside, then, why would the rights of emigrants weigh any heavier on the conscience of citizenist than the rights of immigrants?

P.P.S. If anyone knows a URL for the full Gorbachev-Brokaw interview, please post it in the comments.