Your timeline is a bit off - he got arrested on 26 September 2012 (around the time Satoshi disappeared), and he became a DEA informant after his arrest which is why he didn't finally get sentenced for 8 years.

So at the time of his arrest (after which he was in federal custody and the DEA were monitoring all his use of electronic devices) Bitcoin had only been in existence for three and a half years.

The drug trafficking and Le Roux's various other criminal enterprises all started happened in the mid-late 2000s, before Bitcoin was worth anything