The entire article is discussing potential security risks of WiFi-based IoT devices and electrical safety risks of mains-powered devices, none of which applies to the ZigBee-based Xiaomi devices discussed in this thread.
In terms of security, WiFi-based IoT devices need to be treated the same as computers. Would you toss your computer or your computer's hard drive in the trash with loads of your personal data, WiFi credentials, passwords, etc. still on it? Of course no! Is it a good idea to connect your computer to the internet without the use of a firewall or IP port protection? Of course not!
It's easy to trash talk "cheap" or inexpensive Chinese-made IoT devices, but the truth is that people need to take measures to ensure their security with all WiFi-based devices. Just look at the recent spate of "hacked" Nest cam stories on U.S. national-level news as a beautiful example of how ignorance on WiFi/internet security can come back to bite you.
However, with all the Xiaomi battery-powered ZigBee-based devices, there is absolutely zero chance of gaining access to someone's WiFi network through them. They have neither direct nor indirect access to any WiFi network.
You don't have to take my word for it. I recommend to you what I recommend to anyone who uses any device that uses wireless technology or connects to the internet:
Read thoroughly. Educate yourself. Take time to understand the technology you're looking to use in your life, and how to protect yourself from any security risks. Stay vigilant.