To me, it's not zero deferrals, it's the null set, as there is no opportunity to defer. There simply is no denominator.
I look at it this way:
Will the IRS take a second look if you took the person out of the test? Probably not.
Will they take a second look with an all zeros test? Maybe.
Do I want to take that chance? Do I leave it up to the Client?
To be honest, I've done it both ways, under client direction.