It works by using the processing power of your device (it can utilize both GPU and CPU) to run scientific calculations when you're not using it. It can detect if you're using the device or not and use its processing power accordingly, and you can customize what fraction of your device it can use and when. You can also decide what scientific endeavors (astronomical surveys, protein folding, etc.) are allowed to use your compute power.
That makes BOINC a great way to heat a room in winter provided you're not annoyed by the eventual fan noises (or if you're not in the room), since the energy used will also help scientific research at no extra cost for you. This also means that depending on your settings, it can melt a mobile device battery in no time.
I guess this guy never heard about Popper and the paradox of tolerance :
If a society's practice of tolerance is inclusive of the intolerant, intolerance will ultimately dominate, eliminating the tolerant and the practice of tolerance with them.