Letting freedom and democracy loving Chinese leave China is actually a geostrategically advantageous move.

It's good ideologically - as it exposes Chinese to universal values, rule of law, democracy, freedom of speech, free media.

It's good economically - as these hard working and well educated Chinese move abroad they contribute their labour and innovation to the host countries economies. While sapping the Chinese economy - a phenomena called brain drain.

And its helpful demographically - young people leaving China further exacerbates their demographic problem (aging population).