It's important to understand the context for such actions. Right or wrong, heavy handed or not, there is always a context. On HN and other social media, users always seem to think there is some kind of inherent malice and genocidal intent in every Chinese action, which is utterly absurd.
In this particular situation, the context was 200 Han Chinese being ethnically cleansed in Xinjiang, dragged out of buses and cars and executed on the street while coming home from work, with 2000 more injured.
https://en.wikipedia.org/wiki/July_2009_%C3%9Cr%C3%BCmqi_rio...
There are videos of this readily available.
It'd be like if hundreds of white people were butchered by thousands of anonymous black people for the sole reason of being white in Detroit. What would be the appropriate government response to such an event? Mass incarceration? I mean, in such a context, can "re-education" camps not be viewed as a relatively mild response? This is not to say that it's an ideal response, but certainly it's not the worst an authoritative government could have done.
In response to your point about surveillance, the Urumqi riots began because a false rumour about the rape of two Uighur women in a Han Chinese factory spread on WeChat, fuelling hate, outrage and unrest. Because this is how things work in an uneducated population. Just look up the number of lynchings, burnings and stonings in rural Indian villages based off of false rumours spread on social media.
This is not the same country as your country, these are not the same people as your people. China is a developing nation with an uneducated but heavily interconnected population, a combination heavily conducive to destabilization from both internal and external actors. For this reason, their government will not hesitate to stamp out, censor, surveil whatever it is they need to in order to preserve stability. You can't judge China by the same standards as modern, highly educated western democracies - any attempt to do so is simply naive and misguided.