I agree that on the surface it's more disgusting and would produce a more visceral reaction. From a utilitarian point of view however, the only extra harm done is that he murdered the lion, went home, and then presumably ate meat from a different animal. If he had eaten the lion, in a utilitarian way, there isn't much to separate him IMO.
Of course I accept that no one, not even Peter Singer and definitely not me, can always look at an event dispassionately and come to a rational decision all the time, especially when it's something that's so openly disgusting.
I suppose so but there is also the fact that he did it for fun that rubs people the wrong way - in fact he not only did it for fun, he also bribed a few locals to go out of his way to do it, no less to an iconic species that is nearing extinction. When you correlate all these factors, it's quite different from having a burger.