I am sorry but in neuter it's also an accusative singular. E.g. město, společenství, jednání, dítě... etc. It or that is posible and valid in that sentence.
I must agree. It is not used this way too often these days and native Czechs are now not used to parse these sentences this way, but we do even teach similar stuff in this course.
It is actually accepted in this sentence. It just wasn't reflected in the discussion.