it depend on the situation but yeah a sword that try constantly to squis Zoro'ryou doesnt make Zoro fight easyer (which is what a PU is). Yes Zoro will become stronger but you can't denied that something that can cause this to Zoro, due to not pomping enough ryou or losing focus can be call a nerf:
Look is even causing pain to Zoro. Nah this is a nerf especially if the guy that is using the blade hasnt understand yet what the blade want from the user (which after this spoiler we are getting the answer).
Based on that I can argue that Enma was fighint all the time against Zoro which coudnt use his own power as he wanted and also use the fully potential of Enma.
I can agree that Enma is at the same time training indirectly Zoro control of his Ryou at the cost of losing focus and getting exhausted.