Wouldn't resorting to cannibalism in order to survive starvation just be shouting to all the heavens that you're a massive pussy? Or more seriously, shouldn't the correct response to starvation be prayers to either hobo god to survive the dry spell or to the hunting goddess to find proper food?
Cannibalism is certainly taboo in orc society, but orcs can get incredibly pragmatic about such things when they situation calls for it. An orc who does it for fun is likely to be shunned and probably killed, an orc who does it to survive will be treated a little leerily, but it will probably be forgiven in time.