The sentence "Fustian writing is where you write pompous, bombastic nonsense." is illogical for the following reasons:
1. Fustian, like the sentence implies, means pretentious speech or writing.
2. Fustian writing does not refer to a place.
3. The word where is used to refer to a place.
4. Using the word where implies that fustian writing is a place, which is wrong.
Therefore, one can correct the sentence and say this instead: Fustian writing is when you write pompous, bombastic nonsense.
