If you can't agree on licensing terms, then you sell the watch without the infringing technology. Nobody (relatively speaking) is making a buy/not buy decision on the Apple Watch due to its blood oxygen monitor functionality. It's a feature that isn't important or necessary for the vast majority of people.
If one has a serious health condition that affects blood oxygen levels, pulse oximetry can be useful. For the average healthy person, the medical value is very little to nil.
Most of the above conditions listed above occur in very sick people already under close medical supervision, with the exception of asthma. But even in asthma, pulse oximetry has limitations: https://asthma.net/living/lets-talk-pulse-oximetry
I think it’s cool the Apple Watch has this, but it’s mostly a gimmick as far as I can tell.
There is also value in monitoring stats over time. ie: knowing what's normal for you and even a normal range throughout the day allows you to identify changes before you get to a state where a hospital is needed.
On the non-medical side, I fly small, unpressurized airplanes and altitude can definitely have an effect on blood oxygen levels. Having this data collected in the background as I fly or do other activities is valuable to me despite not having any of the issues presented from the link above.
I have not had to act on the data yet but if I were to get a low O2 alert while flying I would definitely open a window and descend ASAP. Depending on the circumstances I might also consider landing.
