Lecithin is a great additive for a variety of reasons, but you are right. It will emulsify oil and water so it is not suitable at this stage of that technique.
My best oil infusions have been done slowly in sous vide and no water touches the fat. I think lecithin has helped a bit but I am trying to get as many phytonutrients as possible from my weed, and I don't mind a bit of chlorophyll.
Mostly, though, lecithin greatly improves absorption when you eat the oil. Back in the day I made hash capsules and I heard about lecithin, so I added it to some already prepared oil and I was astounded by the increase in potency. I have used it ever since.
That reminds me...its been a long while since I made bhang chai!