And what is wasabi? Other than the Japanese green paste I eat on my sushi, googling "wasabi software" didn't bring me anything relevant, though there were too many results to check them all.
Personally however I don't agree with any service which helps hide criminal actions; sure mixing services have more uses than just helping criminals but ... I don't really know how to feel about this situation.

I'm sure people will eventually come up with something else which will be harder to bring down, after all FIOD did the community a great gift by seizing the bestmixer's domain and letting everyone know they're not safe and that they should build a counter.
They could have keep the mixers running as honeypots and grab the criminals when they though they were safe, it'd probably take a long time for people to realise that these services were compromised.