The "crime" here is not sending packets to DDOS PayPal but criticizing the goverment. The goverment is in turn showing they're not afraid to destroy lives of those who do.
DDOS attacks are pretty much an epidemic on the internet. I'm pretty sure every major company like Google or Microsoft or Amazon has to deal them on a regular basis (http://mashable.com/2009/12/24/ddos-attack-amazon/ for just one example of an attack that was actually successful and well publicized).
Huge botnets make it relatively easy to launch an attack.
This is not some new fact - existence of bots, DDOS attacks on many hosts, that's been known for years and yet this is one of the few times where feds lifted a finger to combat it and certainly the first time where it's done on such a scale and based on such a flimsy evidence and small transgressions like an individual running a DDOS tool (which, by itself, is not nearly enough to bring a website down, it only works if many people are doing it at the same time).
This is not a coincidence and not really that surprising - you fight the goverment, the goverment will fight you.