I finally had a read of this and also looked at the comorbidities listed by the CDC. The top ten do include stuff like "heart failure" that could definitely be complications of COVID.
But they also include some entries like diabetes, which is definitely pre-existing...C19 seems to have some strange symptoms but retroactive pancreatic failure 20 years in the past is probably not one of them.
I would therefore conclude that the comorbidities as described by the CDC are a mixture of related complications, and pre-existing conditions, and without way more detail which is almost certainly not available, there's basically no way to know how that breaks down. I get the Bartlett take and it's probably accurate in many cases, but I also think it's unlikely that doctors are listing "obesity" "hypertension" and "diabetes" as complications of a viral infection.
Unfortunately this really just means that the number 94% is meaningless, and it could represent 1% pre-existing comorbidities and 93% complications, or the other way around, although I think the Bartlett commentary makes enough sense that it is probably mostly complications. Still, if diabetes is in the top ten listed issues, it's definitely not exclusively complications of C19.