There is different types of keto diets, and the ones recommended for "non-sick" people, does not asks you to restrict your protein intake. You should still consume around ~1g of protein per lb of lean mass, probably even more if you are an intense bodybuilder. Only carbs are restricted (often <25g/day), and then fat become inevitably your de facto energy intake.

I also recommend the `Tim Ferriss - Dom D’Agostino on Fasting, Ketosis, and the End of Cancer` podcast, and as you will see, being a bodybuilder on keto does not seems to be an issue. Not for him also.

There is another podcast with him `Dom D’Agostino — The Power of the Ketogenic Diet` but I haven't got the chance to listen to it yet.