Welcome dear Tatty to the best forum you could have chosen for advice on your problem !
It strikes me that your friend had his "time out" for reasons, or actions, that the JW's would not approve of, not for any problem he has with belief.
The thing is , that it is the beliefs he hold that need exposing as erroneous if you wish to see him free from what is in fact a high-controlling ( hundreds of rules) mind control cult. Don't identify it as any of that to him until he has left in his heart at least.
First of all establish if he does believe it is what they call it "The Truth", this is chheky as in fact it was founded on, and is sustained by, lies. Does he believe the claim that it is "God's organization on earth" ?
If he does then such a colossol claim deserves some colossol proof, the kind of proof that would stand up to the most harsh examination in a Court of Law.
If perchance he does not believe it is true then major first on whatever his problem with it was, and then ask him to explain to you how they would prove that it is God's Org.
It could be he is only going back in to re-connect eith his daughter, in which case you need to act fast to make sure he does not really get sucked back in.
Please come hear for advice on any aspect, please listen to B>Sheep's advice, Chris is The Master at getting through if anybody can, despite his not wanting to put the time and effort in with individual JW's, whicjh is the way I feel.
If you stick with him as aproject, we are here for you, and very very Good Luck !