No, he did it by node method. I don't know how well you master the nodal method. If there is a voltage or current source between two nodes, the current or voltage between nodes can be calculated by point conductance or resistance, otherwise it is ignored. In your question, there is obviously only one voltage source and one current source. As for the controlled source, it is related to I2, but when you use the node method to calculate, I2 is zero. To sum up, there is no shortage of short-circuit current, and he has forgotten all the calculations.