If it did require a non-zero focus icon result, it would have been worded something like:
If the attacker has rolled at least one focus result, he may return a focus token to physically pick up all [focus] results and rotate them to [hit] results.
(or: If the attacker has rolled at least one focus result, he may return a focus token to change all [focus icon] results on the attack dice to [hit] results.)
