It doesn’t negate it, but whatever the CoA user touches it the turns it a solid body they can grab.
you can see Caesar can’t just slip away from Luffy. His waist is in a solid body form and he can’t turn it into gas so he has to user his upper body to try to get Luffy off him
In the Enel example whatever Lucci punches would just be a regular body, not electric
Also CoA is literally an armor, that’s how Rayleigh described it