I find this decision by the restaurant a bit odd, due to the response which should have been obvious (bomb threat not withstanding), but I don't have a personal problem with it. My feelings are pretty well summed up by (Tea and Food blogger) Aaron Kagan:
If you're not opposed to eating animals in general, why is this so bad? If they're raised (and presumably slaughtered) humanely and are bred in captivity and not removed from the ecosystem that depends on them, why is eating a lion worse than eating a cow? Is it a matter of intelligence of the animal? If so, it may be that pigs are smarter than lions, but it doesn't make news when we eat them.
Still I really liked (Tea and Food writer) Aaron's friend's explanation about why he thinks this is horrible. It's wordy, and I only post long posts when the words are mine, so go read the whole thing but the gist is:
The fact that a lion could tear me to shreds in a fight - it not only instills me with a sense of fear but a sense of deep respect. The idea of raising these beautiful and mysterious creatures to kill and eat in a commonplace burger feels on a visceral level like cheating. It's cheating nature. It's cheating life. It's ruining the mystery.