You have no idea why it says that and why they put it in the manual exactly the way they do?I just don't think it is relevant because the manual says this is an example. It recommends 0W-20 and explicitly says 5W-20 can be used, but must be replaced with 0W-20 at the next change. That doesn't leave any room for higher viscosity oils.
The amount of sheer ignorance as to why grade recommendations are put in the manuals the way they are put in there is just amazing. People think they are technical and related to mechanical reasons when it is anything but that.