U will not being "cruel to be kind...." (from the song)
Just cruel re-surf board


If I had to nominate 2 things which have bought kite surfing to the masses from its earlier days...
1) Twin Tips
2) Kite Bridles / design 4 easy re-launch.
To have to go toe side to go the other way from day one - most people are stoked when they get up on a board going toes side in the same sentence - OUCH

Try to get hold of a bigger then your usual TT if U have a choice...
Either way get the camera out when he suceeds to do his 1st run - that will be epic

Unless he is already a fish and can think through the solution under pressure - lay down the safety law so he knows what to do JIC.
I loved the feed back from my kids when they got going - have fun.
(In light winds - I used a directional in shallow water as mostly when they get to the end of a beat standing up spinning the board around and coming back goofy / natural was way better than struggling to get up on a TT


)
Cheers
AP

what Cbulota suggests re-foundation with a few lessons is smart if U would not feel comfortable stepping into the shoes of a school instructor.... U will still be doing most of the hard yards as that constant help launching - reviewing the conditions - talking about what to do next / reviewing what U just did i.e. that envelope of knowledge etc etc takes time..