Did you give it a try? You should be able to infuse oil using plant powders. I make oil infusions with matcha tea, and also with ground spices and seeds, for color in soap. I've also used very finely chopped Calendula from the bottom of an oil infusion to add a bit of texture and color to soap. I haven't had luck getting Calendula or other flowers ground to a powder, but I've only tried it in a mini-blender, not a coffee grinder.