Placing your self at an angle to an opponent is considered a strategic position to take. The technique demonstrated here lets you practice taking an angled position as well as using the half step on the front foot. This is a good opportunity for practicing techniques without the overt push-hands element being present. One of the faults of training is the over-training of connected push-hands. We should also be practicing techniques which are initiated in other ways.
These photos were taken while doing the entire technique in normal timing and so the positioning is more natural.
Post script: I think that the blocking arm can also be given some ward-off energy especially if the incoming strike is heavy. Also the turning of your blocking arm to the side can come from the waist. This could be done during the single hand to double hand change as different way of opening into this technique.–