Well as I mentioned, the new method probably doesn't apply to the 10 because Apple probably (barely) doesn't consider it to have enough battery life to include sleep time, so it can't be updated to the new method.
I agree though that the compare tool should ideally be clearer about the different meaning of the numbers. But I wouldn't go so far as to say it's devious because it's likely not motivated by deceit. Apple likely just didn't want to write out the explanation directly in the comparison since it takes more than a few words and the compare tool is meant to be a visually quick and easy way to compare, so they opted for putting it in the small print, which people technically should be reading (even though many don't). Hopefully the very similar low power mode comparison numbers (38 vs 36 hours) directly underneath will give people more reason to check the small print.