I remember finding tons of Reno yaoi on japanese websites when I used to look for it like something like 15 years ago. You could find shittons of it on y!gallery as well. I guess his popularity just died off.
I'm more surprised by the lack of Nero fanart. The character isn't really interesting (nor is Dirge of Cerberus good, to be fair, which might be the main reason for the lack of fanart), but come on, he might be the only FF character who walks around in a full rubber gimp costume.