They did not bake because they are using a rice cooker to evaporate the alcohol. So they are adding heat to it. Usin the rice cooker as the heat source to activate the thc in the alcohol.
Ok so to try an take the confusion out of this. No matter which way you proceed making this tincture. Weather you bake the bud first or not. The alcohol will extract all of the readily available THC and thca from the plant material.
If You bake the bud first then you do not need to use Heat to evaporate the alcohol. You can just let the mixture sit at room temperature until all the alcohol has evaporated from the mixture.
If you do not bake the bud first then you most definitely need to use a heat source of some sorts too activate the THC in the tincture. Which is why they place it in the rice cooker to evaporate the alcohol off.
Therefore while they are heating the mixture they are in turn activating the THC. Turning the thca into THC. So no matter what you need to either pre bake your bud or use some sort of heat source to activate the THC.
I hope this helps you understand this a little better. If not ask more questions and hopefully we can help you figure this out.