Linux systems on the net tend to be servers with lots of available outgoing bandwidth. So Linux systems are very valuable targets for the DOS enthusiast and are quite common. So chances are that this attack only targets Linux systems.

But, yeah, the headline is click bait. Linux systems are known to be quite secure so this is the old "Man Bites Dog" shtick.

Sure, but if the payload in this example is a Linux binary then it won't do anything to an OSX/BSD/Windows machine.

If the payload is an interpreted script, or something that's compiled (if it can find a compiler, etc) then it may be able to infect different OSes.