Again, I am not the right person to ask about Mohawks as I am ignorant on this topic. I could venture to guess that if a similar hairstyle existed for another culture, even if it were the same with another name, and someone from that culture wore their hair in that way it wouldn’t be appropriation.
The issue with PoC perpetuating Cultural Appropriation is not that it is okay, because it isn’t okay for anyone to appropriate another culture; however, there is more tension (at least in my opinion) with white people appropriating Native cultures because their race committed genocide against ours and continue to oppress us.