Since it is Nadal, and a lot of MTF posters hate Nadal, of course nothing will be done about the haters wetting themselves about the guy not playing.
If the shoe was on the other foot, and it was Federer out with injury, and Fed haters were wetting themselves, they'd all get banned in a flash.
Double standards much?
Either way, being happy about someone being injured is fucking pathetic and classless, regardless of fan affiliation. I don't like to see anyone being injured, it is devastating to an athlete, and I don't wish it upon anyone. Karma, people, also basic humanity. In an ideal world, I hope for every player to be 100% healthy and competing at a high level.
Those happy about Nadal, or anyone, being out, they have some issues in their own lives they need to sort out.
The double standard is in your head because that's basically just not true. Someone saying they are glad player X is not playing this tournament, due to injury or otherwise, is not against the rules. Other things they say at the same time might well be, but that in itself is not.