1. Jozu has more than decent CoA feats though. He was able to hurt both Aokiji and Crocodile. It seems a stretch to say that DD is able to outright bust through Jozu's Haki the way Zoro and Law have done.
2. Does that mean he can't activate it, though? DD can stop his opponents from moving, but does Jozu require control of his limbs to use his DF?
3. That's no guarantee that he can't. And we don't know how fast Jozu can change what part of his body is diamond.
1. I didn't say out right I said it's a possibility given DD's position of strength, it would take someone of his level/around his level to be able to fight Jozu. Crocodile's irrelvant and Aokiji recieved a scratch, I'm more than certain DD is capable of scratching Aokiji.
2. You need some sort of energy out put to use a DF, when DD uses Parasits on you yu effectively lose the ability to use energy, we know that you can still think or talk, so if you can show how DF's are telekenetic based or thats how Jozu's fruit works you might have a point
3. Although it still makes the assumption of "Jozu not being able to coat his entire body" a more probable assumption than the contrary based on portrayal of consistency.
Probably fast, but when you are rendered immobilized and your opponent is sitting on top of your back you are likely not going to have the reflexes to continously dodge attack after attack, not to mention DD can probably shoot 5 String Bullets at once and aim them in different locations, could probably do the same with five coloured strings.
If he can't use Haki or His DF when controlled by Parasite he's toast, if he can he'll just slowly die being chipped away at as he tries to block all of DD's attacks.