Red is the Color!

Another misinterpretation!

It is not referred to as a pink coat. The Red coat is referred to as a "pink".  

The Legend of Tailor Pink
Pink can mean the red coat worn in foxhunting (a.k.a. "riding to hounds'').  One theory about the origin of this meaning refers to a tailor named Pink (or Pinke, or Pinque), who invented the design of the outfit.

Collier's Encyclopedia on Foxhunting:
The word "pink'' does not refer to the color of the coat but is a term applied to the state of being formally attired for hunting. It is thought to have had its origin in a tailor by the name of Pink who, in the old days, is supposed to have made the most perfect attire for hunting.

So, if indeed Robin was referring to the color of the coats, they are "red".  Brits use the word scarlet as the colour, and Pink  (Pinke or Pinque) as being dressed traditionally and correct.

If Robin did or does know the term "pink" it would be lost on the American audience for the most part.