It does not matter the least what China considers their waters, this is international waters, everyone has the same rights to be there.
The sanctions were voted for by China as a permanent member of the UNSC, if China did not vote for it, there would be no sanctions.
In fact, the Australian crew whose lives China endangered along with their own pilot is enforcing the sanctions that China levied on NK by proxy.
Maybe China should stay in their own fucking waters if they can't behave like people. Aviation is not a toy for dictators for international dick measuring contests.
Only if you buy a plane, fly there, and start throwing shit on random passersby. By this logic, the crazy hobos own every city downtown. I could see the apologists there.
"Maybe you should stay away from what Methface Pete considers their own backyard! Of course you will get pissed on! What do you mean it's a public underpass!?"