Raul Miller wrote:
Brushing your teeth prevents tooth decay. That doesn't mean that you'll never get cavities if you brush your teeth. Good car care prevents water and air pollution. That doesn't that there will be no water and air pollution [not even from that car]. Etc.
Creating and distributing free replacement for non-free program will prevent non-free distribution.
There is nothing non-ethical in preventing non-free distribution in such a way.
-- Best regards, Sergey Spiridonov