Deterrence and Restraint
I think that there was mutual deterrence when the use of chemical and biological weapons was considered, no matter how accurate the intelligence.
One can appreciate that after the losses at Okinawa, the USA would utilise the atomic force they had to bring the war to an end before the invasion of the Japanese mainland but it is doubtful if they would have used it if Japan had such weapons.
So I suppose the case is made for mutual deterrence.
When the US troops were taking such horrendous and unrelenting casualties at Iowa Jima, Guadalcanal, Peleliu and Okinawa, mostly in trench warfare, it would have been an easy decision to utilise the vast amounts of chemical weapons to ease their problems. I believe they showed great restraint in not doing so.
The result of not using them was a painful and horrific price paid by the US Forces, resulting in uncommon valour being a common virtue