I didn't think about this, I agree with this interpretation.
Kabuto doesn't say that the Regenerationn was slowed down, he explicitly says that Naruto's power means the Regenerationn will take longer.
That can easily mean that due to Naruto's destructive power the damage is greater, thus the Regenerationn time is increased due to healing the greater damage.
Also, Muu had peformed Fragmented right upon being hit by the Rasengan. Fragmenting is detrimental to Muu as it literally cuts his Chakra by half. This is a huge issue to Muu as he can't even peform Jutsu due to Fragmenting. This could be another reason for his Regenerationn having a greater duration.
Also, Naruto has hit other Edo Tensei before with his Rasenshuriken, something more potent than his Planetary Rasengan that does not have the potency of Rasenshuriken, yet the Rasenshuriken does not delay the Regenerationn of said characters.
I completely disagree with Limited Regenerationn Negation now.