I'm not talking about legislating when people use putters, at all.
I'm saying that people use all sorts of definitions for "putting", when arguing that putting in disc golf is easier than in golf, or not.
If we say putting is any shot where a putter is thrown, the made percentage goes way down. It's not a good definition, not one that I would use, but it's about as valid as any of the others.
Putting can be defined as inside the 10-meter circle, or where a certain percentage of shots should be made, or where we'd expect to hole out in 2 shots, or where putters or thrown, or some arbitrary line (20-meters, etc.), or God knows how else. None are definitive.
Seems that circle 1 and circle 2 are good definitions of putting. Even if the player doesn't use a putter. There is no rule as far as I know in regular golf that says a player needs to use a putter on the green.
These discussions further convince me that disc golf and regular golf are two distinct sports.