All this together makes me believe that Rumpel in a red robe may symbolize him being somehow in a position of a “judge” in some capacity by which he studies events that occurred, and is responsible for carrying out (his own faulty version of) justice.
Some nice points!
My first impression of Rumple’s robe was also ‘Sherlock Holmes’ type attire, especially that Sherlock is normally portrayed with a magnifying glass too. All Rumple’s missing is the hat and the pipe!
In a sense Sherlock association does tie in with your impression of ‘judge’.