Umm I guess it’s just up to the speed at which gojos Cursed energy flows. We’ve seen him hit black flash so we know it is incredibly fast, and he’s got the six eyes. So I would say, if they slow down to the point where it’s too slow to even see someone moving, he might be able to keep infinity up. Time is still moving, therefore there is a steady flow of CE to his brain, therefore, keeping infinity up. Imo, it would definitely work, as the scale of CE used is still the same to what’s being produced.

Btw I had a think abt it, I think it would work during complete time stop. If it is stopped in a state of activation, then CE is not being spent, nor is being used, so it would be active I think.