Yes, that has direct precedent. And with the most obvious precedent, was the alternative taken when that group [surprisingly! /s] didn't do what Gandhi thought they should have done.

Edit: but that isn't nonviolent protest, it's just leaving your home. It doesn't cause any political change, and it's not at all the logical extreme of nonviolent protest (the logical extreme is stupid, and seems only to have ever been carried out by millenarian cults, but hey ho).

I know the Chinese government has caught a few escaping by boat, and others have made it. It seems they are against even individual migration.

I would love to give those people a home. People seeking freedom are the ones I want in my country, much more than the powerful people trying to seize more power for themselves.

I would assume China is monitoring all their Hong Kong citizens and carefully scrutinizing them for any dissident behaviour before they even think of letting them leave the country.