It all depends on whether this is your steady mechanic that you trust. A mechanic you don’t know should call you before he does any work to let you know what he is going to do and how much it will cost you. A mechanic that you normally go to and normally fixes your car does what he thinks you want him to do to make your car safe and in working order. In that case, he does what is needed and you pay him for it.
I don’t know what rotors are, but if they needed to be cleaned, and could have caused the noise then they should be cleaned. Cars need regular maintenance and if you neglected to give it the care it needs it will cost you in the end. So it is all a matter of trust. Either you trust him or not. If you don’t you can ask him to show you the proof that the tires cost more or you want to pay the agreed upon price, or that you don’t want new tires at all.