he could still be in transit.
If he's still in transit, he has to be someplace between the start and finish.
If he's someplace between the start and finish, then he has not done all of Zeno's steps.
Thus, if he has done all of Zeno's steps, then he's not in transit.
The key thing about the real numbers, that you are not using, is that they are
complete. Intuitively, that means they have no "holes"; this is usually stated as follows:
If A and B are nonempty collections of real numbers, such that A lies entirely on the left of B, then there is a number c seperating them.
More precisely,
Let A and B are nonempty sets of real numbers
For all a in A and b in B: a < b
Then, there exists c such that
For all a in A and b in B: a <= c <= b
This can be used to prove the Archmedian property; every number is smaller than some integer (and is thus finite) as follows:
Let A be the set of everything smaller than some integer. (Note that all integers are in A, because n < n+1)
Let B be the set of everything bigger than all integers.
Assume B is nonempty.
Then, there exists some c seperating them.
Thus, a <= c <= b for all a in A and b in B.
Now, c is either bigger than all integers (and thus in B), or it's not (and thus in A).
If c is in A, then it is smaller than some integer. Call it n.
Because c < n, c + 1 < n + 1. Thus, c + 1 is in A.
This is a contradiction because c + 1 > c, but because c + 1 is in A, c+1 <= c. Thus c cannot be in A.
Thus, c is in B.
c - 1 < c, so c - 1 must be in A. c - 1 must be smaller than some integer. Call it n. Because c - 1 < n, we have c < n + 1. However, n + 1 is an integer and is in A, so n + 1 <= c, which is a contradiction.
Thus c cannot be in B.
So our assumption that B is nonempty led to a contradiction: there's a hole between the finite and infinite numbers, but by definition the real numbers have no holes.
Thus, we conclude that there are no infinite numbers; every number is smaller than some integer, and thus the Archmedian property is proven.
Now, we turn back to your question. Suppose 1 / ∞ = e > 0. (whatever 1 / ∞ may happen to mean).
By the Archmedian property, 1 / e is smaller than some integer. Call it n.
Because 1/e < n, e > 1/n.
So, if you insist on maintaining that 1 / ∞ > 0, then there exists an integer n such that 1/n is smaller than 1/∞, which is absurd!
Roughly the same argument is used to prove that \lim_{n \rightarrow \infty} 1/2^n = 0.
(More directly, if you maintain that ∞ is a real number, then I could simply apply the Archmedian property to produce an integer bigger than ∞)