If he's done with the contract (after completing filming of course), and not interested in renewing/continuing, why would he, or the studio care when that piece of info gets out. (IE - It's no big deal... "I signed to do 3 seasons...I did 3 seasons...")SFX is a British magazine. The article hadn't been intended for wide online distribution.
Surely Sir Patrick knows when to keep his mouth shut about sensitive matters.
It's not new news in that everyone stated (the Studio, the Producers, and Patrick Stewart) before the first season started production that Patrick Stewart signed/agreed to do 3 seasons of Picard.