If you're referring to this article, the maintenance schedule calls for thoroughly washing the box with detergent, then rinsing before spraying the bleach solution. If you are concerned about any residual bleach triggering a chemical reaction with subsequent urine contact (highly unlikely at the suggested dilution), simply rinse the box several times after using the bleach solution and dry thoroughly. Alternately, wash the box again with a mild detergent solution, then rinse thoroughly and dry.
As to the advice you read on never using bleach to clean litter boxes, a number of articles by other experts tend to refute that statement:
The Litter Box
Cleaning the Litter Box (Lisa Pierson, D.V.M.)
Litter Box Wars
Bleach: A Cleaning Mainstay
Cleanliness is Next to Catliness (Paul D. Pion DVM and and Gina Spadafori)


