Squirting water does not harm the cat… just like it would not harm me. The difference is, you can talk to me and explain to me not to bite my nails.

If you read my post again, you will see I advised this as it would concern me that sucking his tail could cause him to get sores on his tail, if this is the case, it would be in the cats best interest.

Just like when you stop a child from sucking their thumb, because it can have adverse effects such as sticking out front teeth.