It's impossible to know what the motivation was. It could be as simple as someone unable to keep it all quiet inside the UCI. A sort of knowledge-is-power and this is how someone displays that political power. The *wildly* inconsistent anti-doping actions from the UCI coupled with the known widespread corruption just makes things more uncertain. Here's a fresh example:
http://www.cyclingnews.com/news/uci-wants-georges-ban-extended-to-two-years
The tendency is for the UCI to sanction lower-level riders to manage doping at the elite level. IMHO, we saw it with the Colombian sanctions in 2013. That's about the only consistent thing the UCI does in regards to anti-doping.
JTL is right to be angry even if he doped for his Sky contract. Or, maybe he didn't dope for the Sky contract and Sky's training volume demands doping which got him nothing but fatigue.
Or, as coineach hypothesized, Sky doesn't want him around and this is a great way to end a contract.