Cool post. One thing that rubbed me the wrong way: Their response was better than 98% of other companies when it comes to reporting vulnerabilities. Very welcoming and most of all they showed interest and addressed the issues. OP however seemed to show disdain and even combativeness towards them... which is a shame. And of course the usual sinophobia (e.g. everything Chinese is spying on you).
Overall simple security design flaws but it's good to see a company that cares to fix them, even if they didn't take security seriously from the start.
Edit: typo