Even though Hulk was given to Fox, Adrian didn't just let it go, so he recommended Joss Whedon as the writer and director for this movie. In the eyes of others now, Whedon might only carry the label of a producer of Buffy the Vampire Slayer, but Adrian was well aware of his future achievements.
News Corporation and AC Media don't get along, that's a matter between two media groups; Universal and Fox haven't ruled out the possibility of cooperation in film matters. So even though Adrian initially gave Hulk to Fox with a mischievous intention, he still recommended Joss Whedon to them. Because of this, Fox agreed unanimously to his recommendation without hesitation, and the Miracle Director's vision has pretty much become a golden brand now.