If you are always playing together playing scholar should be fine with the added benefit of the fairy.

Though eventually he might get access to a lot of abilities he doesn't have to use all of them.

If one of you is playing tank in your group with him you can play paladin with him, later on you get clemency as a paladin that can help your brother in sticky situations with heals. They also have other support abilities to make his experience smoother.

You can bind dps macros for his dot and casted nuke like suggested for white mage so he can target the tank mostly, then bind adloquium and lustrate for single target healing. For aoe succor. You can even leave out lustrate for 4 binds.

Of course summoning the fairy is an extra bind, but once it's summoned it will stay out unless he dies.

With the above he might have to spam the heals more and not dps as much, but if you are doing mostly normal content and you pull dungeons at his pace you will be ok. It might be a bit slower but it would be doable.

If you or your other brother has a healer one of you can heal with him in content with 2 healers.

Its perfectly fine for him to play with limited binds if he gets to enjoy the game!