For a deeper look into our World Check One API, look into:
If the WC1 profile is deleted from the one of the matches in the result set of a case, no update notification is returned on the OGS monitor API.
What is the probability to have that developed in the future? If we are using OGS to not hit WC1 server when there is no update, we lose that kind of removal scenario. The only way to identify that is calling the profile API and getting a 404.
You are correct that the only way to find if a profile has been removed is to call the profile API and get a 404 for it.
I will write to product management and discuss with them if this can be an enhancement.