Every decade Bowie evolved musically. Always taking chances, always doing what he wanted and sometimes ahead of the curve. I would say it applies.
That in and of itself doesn't make someone a genius, it just means they evolved musically, took chances, did what they wanted and were ahead of the curve.
What also needs to be said, and I believe it's something kingshmegland would agree with, is that with every change and innovation he absolutely delivered in terms of quality of music. Pretty much every genre he dabbled with fit him like a glove, he always found a way to embrace new styles and different "colors" while still maintaining his own signature characteristic.
I'm about to throw in a bunch of tracks to illustrate how insanely diverse he was over the course of his five decade career and without exception managed to put out good stuff whichever style he pursued. Feel free to go through the following songs whenever you find time or will: Starman, Rebel rebel, Station to station, Ashes to ashes, Loving the alien, Miracle goodnight, Dead man walking, Something in the air, Valentine's day and Blackstar. Every single song is in its own universe. I know it's quite a list, though, sorry.