It's more than just zero. Every number can be represented in multiple ways in DEC64. For example, you could represent 3 as
3 x 10^0
or
30 x 10^-1
3 x 10^0
or
30 x 10^-1
If you're scared of normalizing before comparisons, or somesuch, nothing stops you normalizing around operations instead, like standard binary floats. Only you'd probably be shooting yourself in the foot, since you'd probably end up normalizing more and making the ‘integers are fast’ claim fail.
(In fairness, for small integers, the operators over normalized values are closed — they always return normalized values)
> (In fairness, for small integers, the operators over normalized values are closed — they always return normalized values)
Normally normalization refers to using the smallest possible exponent; in this light small integers are unnormalized.