The point is, they said they would not cover Covid19 as it was not listed.
So, when you check your insurance policy details to make sure you are covered, how do you do that when the bloody disease you want to insure against the effects of hasn't been discovered yet??
I haven't and wont be reading the schedule you referred to, but with reference to Covid-19 (the disease) I suppose it would go like this ...
Coronavirus (which is the cause not the disease) is a range of viri and cause several respiratory illness such as the previous SARs and MERs diseases, along with the new Covid-19. So you could have cover for diseases caused by
all Coronavirus, and further you could specify only known diseases, or cover any unknown (novel) diseases as is the case with Covid-19. Or you could restrict over to known diseases only, and keep the premium down
If the cover is important to someone for some reason, then I am sure they will have procedures in place to check that cover they are getting and what they are paying for.
Compare with Critical illness insurance which may be more at our level. The types of illnesses covered, and how cover is provided is clearly specified and itemised, so its clear when the policy will pay out. So yes you may get a "critical illness", but if it's not in the schedule - whether its been discovered or not, then the policy wont pay out. Or you could add specific risks and cover to a policy to get non-standard cover, but the premium will go up to reflect the added risk to the insurer. That's how insurance works.