You can turn off those notifications and even create a "Sick" focus if you want.
Further, you can adjust your goals when you're sick and even think of them as "Do not exceed" goals.
What Apple shouldn't do is have the same metric for achievement be used to indicate when you haven't achieved something. In other words, if you sprain an ankle, it should still show that you were unable to do X number of steps, not reward you for doing a good number of steps for someone with a sprained ankle.
People here all the time seem to think having an excuse is the same as actual performance. It isn't. It may be the reason the goal wasn't achieved, but it's worth having a record of what you're actually doing instead of mixing excuses with the metrics.
As a ladies man, I put the ribs on top, which is outside and is more attractive for any lucky woman who may be checking out my watch. In other words...
It's ribbed for her pleasure.