I mean, really.
I have no doubt that Indians used more of the antelope than cowboys did (after all, cowboys could often buy better stuff at the general store than could be made out of bone and hide), but "only the tongue"? That doesn't pass the smell test.
Why would a bunch of cowboys, having gone to all the trouble of shooting an antelope, throw away all that fresh meat, rather than, oh, I dunno, say...*eating* it (or, if they were on the trail, eating as much as they could eat before it spoiled)? It's not like cowboys on a drive suffered from a surfeit of delicacies.
So, Mr. Bergstrom: ideal teacher, or lying sack of crap?