Originally Legacy of the Dragonkin was created to be GoG lite, which is why it blocked GoG. Since then GoG has be completely reworked, and the power of Legacy of the Dragonkin has been lowered as well. I really see no reason these two things should not stack at this point.
Having said that, I don't really think it matters what was or wasn't intended for something that is over 5 years old if it doesn't make sense with the current game.