I would say that a usurper returning from exile to reclaim the throne unquestionably represented an enemy as far as the Bourbon monarchy was concerned; certainly taking the 1815 episode in its entirety. It's not as if Bonaparte came back to France just to collect some clothes; and Ney singularly failed to bring the monster back in a cage. Tactless, really.
I think describing a monarch withdrawing out of harm's way during a coup d'ťtat, however craven an act, as 'desertion in the face of the enemy' is stretching a point, especially given recent Bourbon family history, Only those enlisted or commissioned in the service of the Crown (as was the case after the Restoration) can be accused of desertion. It is a military crime specific circumstances.