Have you had a look on the thread that lists local providers to see if the lad can get subsidised training? How severe are his balance issues? If he has a BMX does he already ride it at all? Do a bit of searching and see what Cycle Training is available to him. Learning to ride is not that difficult if it is taught properly. Quite often the presence or help o someone the trainee knows is actually counter-productive. Lastly, does he want to learn to ride?
An excellent point sir