I am surprised that nobody else has commented on this quite extraordinary event. It is certainly rare for the head of a house (or someone who claims that honour) to alter his coat-of-arms.

I can only imagine what might have been said if the Duke of Parma had made a similar pronouncement in respect to the arms he uses regarding his Spanish claims.

Perhaps people did not want to speak ill of the dead (since prince Henri died within a few months of this change).