What happened was someone tweeted a question at him wondering if there were any LGBT characters in X-Men: Evolution and his answer included the reveal about Laura. No need to get out the tinfoil hat.
No, he's not. From NYX #3, Laura's first comic book appearance:Kyle and Yost created her for X-Men Evolution, where she appeared first, so he does have (co-)creator credit (and sorry, XCE, but Yost IS credited as a creator as well).
From Innocence Lost #1:
The latter even makes a point of clarifying that the origin story was created by Kyle.