I don't listen to the Rocket regularly anymore but I had it on for a bit the other day and musically it sounded the same. I've certainly heard the Foo Fighters and even more contemporary rockers on there in recent years.
Being old and set in my ways, classic rock will always be music from the mid-60's to the late 70's, but of course what's "classic" changes as time progresses so I guess technically Foo Fighters, Nine Inch Nails and GnR are all "classic rock" in age if not sound.
I suppose it could be a move to position themselves closer to TK 101 and further from the classic hits of Cumulus' Jet.