Well, I think I like the consistency this rule brings. I consider both DROTs and wedgies to be "bad" putts.
My concern is for shots that enter above the top of the tray and then wedge in the side. They can be supported in the same fashion as a wedgie entering below the top of the tray. (I've always called these inner and outer wedgies

.) It may be that most inner wedgies have a majority of the disc on the inside and that most outer wedgies have a majority of the disc on the outside, but in both cases, the disc is supported by the same surface of the tray: the part of the tray bars that make up neither the inside "wall" nor outside "wall" of the tray.
As written now, I'm not sure the rules give any room for an inside wedgie to count as "in", even if witnessed. And, if the rules can be interpereted such that inner wedgies count. Than also outer wedgies should count as "in" for blind shots where there were no witness as to how the disc became wedged.
Any thoughts on this....