To me it's unbelievable that a cyclist would transport his vulnerable child along in some makeshift contraption, no doubt, on what is a main road, in fast moving traffic.
Of course the cyclist can ride properly, but he cannot predict what other foolish people/motorists/motorcyclists will do next. He doesn't want to consider his vulnerability, nor that of his poor children.
The least risky choice would have been to try to reach the pavement and dismount. If it is potentially dangerous to swerve or move our into the road, to avoid a vehicle, then you should do it as a last resort. But, it's obvious to me now that cyclists do not like to stop, once they have built up a momentum. It probably unbalanc s them, makes them feel less in control, and loses all that lovely momentum which makes them think they are flying . It conceivably would wobble the contraption to do slow it to a stop.
Cycling on main roads isn't illegal, but it ought to be and building safe and dedicated cycle paths ought to be prioritized by Councils.
Secondly, bikes and motorised scooters have spread their bad habits to motorists now. Motorists do not stop when somebody is on the crossing. The drive on through expecting pedestrians to second guess their plan. They put up a hand to acknowledge you, knowing they are in the wrong, but not wanting to break their speed and thinking, cyclists do this: why shouldn't I. It's terrible what cyclists have done with their selfish and entitled behaviour.