The Chinese are picky when it comes to toilet paper

Chinese scholar Yan Zhi Tui (顏之推) mentioned his choice of sanitizing medium in his writing from the 6^th centry:

其故紙有五經詞義及賢達姓名，不敢穢用也

I wouldn't want to use anything with classical text or honorable poeple's names on to wipe myself

What was he thinking? Was he caught going into the stall with his conference proceedings and came out empty handed?