Personally without evidence I'm inclined to write this off as an urban myth on par with i ate a big Mac once and now weigh 20stone therefore MacDonalds are responsible for me being a lard arse (I'm not BTW!). Could start another one, I use OEM fluid and my clutch failed therefore OEM fluid causes clutch failure
The official technical reason given for the dye was merely to make a visible difference to aid fluid changes and i cannot see an extremely small amount of dye necessary causing anything, it's a colourant not an abrasive. It is quite common that two stroke oils used for scooters, mowers,chainsaws etc are coloured green red or blue so that you can see when it is mixed with fuel. similar tax exempt DERV is coloured and I've not heard anything attributed to that
The official reason given by ATE for the withdrawal of the Racing Blue was that it was found to be non compliant with the American SAE spec for brake fluid which calls for it to all brake fluids to be a yellow/clear colour ONLY to differentiate it from other fluids and no other reason. It was actually on the US market for several years before someone spotted this!
It is worth pointing out that vw specify the old DOT4 standard as being suitable but there is a newer DOT5.1 standard that is far better than the old one in Dry and Wet Boiling points which are often quoted as being important. for hard braking performance in a road vehicle (vapour locking in hot brakes)
although Racing blue and the current ATE typ200 are "only" DOT4 the factory spec for boiling points is well in excess of even the new DOT5.1 spec so I wouldn't have any issue using it