The epic-ness of a mammoth steak in that setting makes up for any lack of flavour.
Also, it will get you extra publicity just for serving it. Sounds like win-win to me.
Ah, but where would be my chance of being gifted a Michelin star? I'm not a student in the school of "no such thing as bad publicity," but feel free to serve mamoth steaks in your cro-magnon cave restaurant.