Hmm I generally only use wireframe and grasshopper.
From experience with running a large grasshopper script, having the extra cpu and ram was significantly more useful that having any graphics. In fact, my laptop with the newer cpu and slightly more power, but on built in graphics runs my scripts in shorter time compared to my pc with the extra graphics.
If the user is more into just Rhino, I guess having a graphics for display would result in a smoother experience. Based on his description and use case, I think the smoother graphics would probably be more in line with what he will be doing. so the ideapad actually looks like a good pick. Maybe just have some stand so that the laptop isn’t sitting on the desk without airflow.