That's actually a good advice, there's nothing laughable about it.
If you happen to have a Bluetooth mouse (the same goes for keyboards), then just pair it with your device and use it.
Also, any USB mouse will do, you just need an OTG cable for your Android device if you don't have one yet and of course, your device must be OTG capable (most of the modern Android devices are).
I've used both - keyboards and mice on several different Android phones and tablets, both USB (wired and wireless RF mice and keyboards with USB receivers) and BT devices, too.