I think the rule was meant to be used in association with fighters actually getting up off the ground and being unprepared for a big hit. But, as in all 'rules' there are loopholes that people find to exploit. So these guys like Dodson will bend over when they are in a bad position and sneak a hand down quickly to either A)stop the knees and/or B)catch the aggressor off guard and get a point deducted/warning, since the guy on top can't always see or feel the hand going to the ground. Which I think is bogus bullshit. That type fighting is just as bad as intentional groin kicking and eye gouging in my opinion. Or better yet, crying foul about something that didn't really happen, like a groin kick that landed on the thigh or something of the sort.
So yeah I agree that this rule should be removed/changed. Change it so that it is only in affect when the fighter is getting off the ground from a knee position or some shit. But not in affect when they are just standing there looking for invisible protection of sorts.
I also think the Ref made the right call in just a warning. Because Dodson was defending and just using the hand as a quick throwdown like I stated above. This was not the changing factor in the fight, it didn't seem to take away from Dodson's game one bit. His winging punches and constant running/backing did however.