How is the 3rd Discourse Connected with Emptiness?

How are dispassion and liberation, as taught in the 3rd discourse, connected with emptiness? 

1. The aim is to be empty of, for example, anger.

2. Trying to suppress anger is just the habitual doing that one steeped in ignorance does do. (I speak in this from plentiful personal experience.) But true mindfulness is, in the first place, the mindfulness that long is long, short is short, feeling bad is feeling bad, anger is anger, a weed is a weed and, ultimately, a flower is a flower. 

True mindfulness is empty of trying to be right, empty of trying to suppress anything. 

3. Anger is dependently arisen. As such it is empty of its own substantial existence as a thing-unto-itself. 

Again, anger is originally empty: there is no such thing as anger that is worth worrying about. 

(“Oh, but I dooooo worry.”)

4. Intellectual recognition, based on the doctrine of dependent arising, that anger is empty, is not the point of sitting practice. The point is cultivation of what is to be cultivated. The point is cultivation of the real wisdom of emptiness.

As Nāgārjuna put it: The ending of ignorance is because of the cultivation of just this wisdom (avidyāyā nirodhas [tu] jñānasyāsyaiva bhāvanāt). And cultivation, whether of the wisdom of emptiness or of potatoes, takes time and sustained effort.

At the same time, the ending of ignorance is because of the bringing-into-being of [the wisdom of emptiness as] just this act of knowing (avidyāyā nirodhas tu jñānasyāsyaiva bhāvanāt).

And perhaps this was why it was possible that right there and then, as the Buddha delivered the Instruction about Burning,

tassa bhikkhusahassassa anupādāya āsavehi cittāni vimucciṁsu.
those one thousand monks' minds, through not clinging, were freed from the polluting influences [of desire, of becoming, and of ignorance].