Yes, in order to successfully take over, one has to be wresting control from an objectionable monarch. Clopin knows that he has the ardent love of the vast majority of his people. Even if someone did succeed at killing him, he doubted that the gypsies would be content to just allow his usurper to take the reins.
He chuckled to himself, eyes dancing across the horizon. He knew when Esmeralda was kidding. "Oh my, I haven't told you? An assassin came for me yesterday. I would mount his head on my wall, but he's absolutely hideous, so I suppose I'll just settle for tossing the body in the woods."