Zeno's paradox was trying to explain that you cannot trust your senses, and that what can sometimes be seen is not what is. He based this off Pythagoreans and their abstract geometry...
Sometimes when you use the pythagorean theorem, if you actually go and measure the hypotenuse, you wont find the number that comes up with the forumula (A squared + B squared = C squared). As in the instance of a right triangle with the measurements: height = 1, length = 1. The theorem would turn out to be a non-whole number. If you physically took a ruler and measured the hypotenuse, then, you would not get the exact same number as you would with the abstract method of the pythagoreans.
So Pythagoreans would say that you can only trust your abstract thought, and not what appears to be. Zeno's point is similar: Not everything is as it appears. So even if it appears that Achilles beat the tortoise, this would actually be false because of the mathematics and abstract calculations used for this specific paradox.
When it comes to calculus in solving this paradox, there is still an issue. Within a finite measurement, there are infinate possibilities. I've only heard the one argument against it:
If you place polls at every step you take, say you put down one hundred polls, and you take a flashlight. The objective is that at every even poll, you turn the light on, and at every odd poll, you turn the light off. Then by the time you get to your very last poll, the light will be on. This indicates that there is still another poll ahead because there are only two settings on the light. So the journey is never complete.
This is Zeno's point. The journey is never complete, no one can finish something... and because of this, he rejects the idea of motion and change. Because if there are infinate journeys within one journey, then you will never finish the one set ahead of you. There is always something else.
So it's more of a matter if you follow abstract thought only then time is not a matter. Time does not enter into what is eternal and universal, like numbers. So how could one possibly apply that thought to observation, apparent reality? The two conflict. Both things are very real, but you have to decide if there is one you side with more, to determine how you see the universe and what you believe to be real and true.