New picky tenant painting demands - Help!

[Malcom Smith]

Landlord here: I've a new tenant moving in next week and during the walk-through he points out some minor issues on the walls in two of the rooms (previous tenant hung pictures so there's some pin holes and marks on the paint). So he wants those rooms repainted and also wants his bedroom repainted a different color.

He has a "painter friend" lined up to do the work so I offer my tenant $450 toward painting the two rooms and tell him he will pay for the color change in the bedroom as that's personal preference (nothing wrong).

Tenant says that's not enough money for his painter who wants $450 per room (total $1350) so we agree in writing he will pay me the $450 for the bedroom and I will get the painting done, covering the cost of the other two rooms myself (I know I didn't have to do this but I was trying to be nice).

So I paint the rooms myself (they are perfect) but he's now refusing to pay saying he thought he was getting a professional painter for his money.... and wants to pay me less.

He hasn't even moved in yet and I'm very worried I have a needy problem tenant. Am I within my rights to do painting myself? He has signed an 18 month tenancy agreement but not paid security, rent or the agreed painting cost. 

Can I withhold keys if all of this is not resolved before move-in?

Exasperated...