Moku watched this battle coming to a climax with blazing eyes. He didn't want to miss a single moment because he liked it.
When he was still a human, apart from fighting Moku also liked watching other people fight. Especially those with excellent fighting skills. From there he will get inspiration to create new moves that he can use for his next fight.
There's a reason why the Mutated Wolverine's second mana organ doesn't appear even though he's been badly beaten by Boku. This is because the mana organ is not very useful for close combat.
The Mutated Wolverine has sharp spikes on its back which can also be used as armor against enemies taller than it. However, against a much smaller Boku, these spikes won't be very useful.
Then when he wants to use both hands to claw Boku, then standing on two legs is better than having to crawl on four. Especially with an enemy that has a faster speed than him like Boku.