The relevant section of the news article is:
Cyclingnews.com has been sent a letter purportedly from Floyd Landis to a senior cycling official with revelations of drug use in cycling in the period up to his Tour de France victory. We are awaiting responses from individuals involved and hope to bring you full details shortly
So it says the letter is purportedly from FL, meaning they're not sure, which is a big problem IMHO.
What
is clear is that it was to a 'senior cycling official'. No hedging there. That might point to the source of the leak.
Moreover, as I understand it, the letter wasn't sent directly to CN (although the wording is a bit unclear).
The best interpretation I can come up with is that:
(i) the letter was leaked to CN by someone on the recipient's side (with or without consent by FL is up for debate).
(ii) CN has not confirmed independently the authorship of the letter. Probably they contacted FL, but maybe he wouldn't confirm to them, which means it was probably leaked without his consent.
(iii) CN has strong indications that the letter is the real deal. Maybe they have a second source, or maybe the primary source (or the content of the letter) provided details which can be checked independently. Otherwise, why publish this snippet?
(iv) The 'awaiting responses from individuals involved' phrase seems to point to that FL spilled the beans. He mentioned names, broke the omerta. They want to give people the chance to respond to the content of the letter.
This could get interesting.
ETA: any idea why it was leaked to CN in particular?