My passive agressive sister

We are having the main bathroom redone, and the plumber who was here the other day used a microfiber cloth that was in the bathroom that my sister considers HER towel to block the drain so that water could not go down it since there was no pipe below due to the repiping going on at the same time.

She was upset that HER towel was down in the drain and she put this note inside the train. Um. I took it out and threw it in the trash, she wrote another, and then I saw it later and told my dad. He told her that would only make the plumber mad/cause for bad service and it was good since microfiber towels absorb a lot.