Definitely on his own. He was never touched, or even close to it. And to answer ravi's question, he did it at that weird angle because he fell at an awkward angle making a touch catch, and was just trying to propel himself to the sideline in any way possible ASAP before the clock ran out.
The guy wasn't "giving himself up" like after an INT or something. He obviously was trying to get out of bounds to stop the clock, which he did.
No, the Bills still wouldn't have won, but that doesn't change the fact that it was a horrendous call.