Would you fire this guy?

I work for a commercial cleaning company. Several months ago I was working with a guy. He's pretty severely autistic, but he's able to work, and do a good job for the most part. Anyways, there is a small cup that has a toilet brush inside that we use on the toilet. There is a little white brush with it, to scrub the outside of the toilet. There is a black brush that is for scrubbing sinks. Well, This guy put the sink brush in the toilet cup which I think is disgusting. I tried telling him, but he was like "im training you". So I told my boss about it and the next time I came to clean, the brush was in its rightful place so I figured it was taken care of. Fast forward to today. I'm at the same place covering for this guy because he's on vacation. The sink brush is in the toilet cup again. My boss has since quit, and the hr manager is now my boss, so I was gonna tell her. She probably knows about him doing this for the first time, so it will be his second offense. I don't know. I would feel kinda bad if I got him fired, but maybe that would be best for the health of our customers?

Would you fire this guy?
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