Now I do similar for the kids, though I have now progressed from holding the centre of their bars as they learned to ride, to pushing on the back of the pannier rack - but their bikes are a bit bigger now as well...
- Cycling with one hand at the back of the stem of his Isla bike.
In this pic I was just his confidence back up after a tumble... only a few minutes later he was flying along well before he realised I wasn't holding the saddle anymore, and had fallen behind to give him more lateral space.
He really didn't want to learn early.