It makes Freeza seem a bit too special. Giving him a higher potential than the main character is a bit much, and it would have been better if he used the special golden power up to get that much power rather than just training. It also raises questions about why he didn't do it before. These questions can be explained by just saying he was overconfident, but it seems like a cop out.
The Godmode equivalent is a
better asspull than just 4 months of training, because then it isn't like Freeza was inherently Godmode and never even bothered to train for just a day or two to beat the SS when he was revived. It could still be that way, I suppose, if Freeza just
thinks training is that good, but he can't actually get anywhere, and they give up and ask the dragon again for a way to power him up; it turns out to be the God-alt power up that takes him past Buu and then all the way up to Godku's level. That would be more reasonable.
Despite Freeza being in a fucking cocoon of all things, we've somehow devolved into menial power level debates
I'm not sure there's much to debate. We can speculate, but with completely new things like a cute parade to torture Freeza there's not much to go on, so we'll just have to see the movie (or see more pages) to know whether there's actually anything to the cocoon.
To completely make up an answer: it's like the cocoons Buu uses to extract energy - only Freeza is conscious since it doesn't cover his head - and this device is used to weaken Freeza while allowing him to be tortured with his body present, but not allowing him to be dangerous. Why is his body present in the first place? Maybe really bad villains get tortured, and to be tortured you need a body? But I just made that up and it'll never actually be explained in the movie!
The other thing to note in this page is that Freeza has no halo.