Plenty of the >0.5% results have serious sampling problems of themselves. The Dutch study sampled people who were donating blood. The subset of the population that donates blood is could easily have different behavior than the general population: like being more health-conscious and thus less likely to be infected, which would inflate the infected fatality rate.
And when we compare against the flu, we also have to consider that there are different methods of estimating the infected fatality rate. More conservative estimates on infections of the seasonal flu yield higher IFR values. The epidemiologist being cited here is providing relative estimates of 0.04% and 0.2-0.3%. We could go with more conservative estimates on the infected rate for COVID-19, but we'd have to be similarly conservative when measuring the IFR of the flu.
I'm not sure the blood sampling would skew the direction you think it does, healthy individual could just as well mean that they're more likely to have had it since they're less likely to sit at home and stick to a quarantine. But you are right, it definitely counts as a sampling issue and I'll concede that ranking by quality is a lot less clear cut, I should not have been so confident
Initially you were implying that the IFR of the flu was 0.1% and comparing it to an IFR of 0.4%, this is what I disagreed with strongly
The bloomberg link you're giving is showing that the vast amount of randomly sampled serological studies are showing IFR of 0.5%-1%. And importantly, looking at how the random sampling has been done for each case and ranking by quality, >0.5% results rank at the top (he studies with the biggest sampling problems show the lowest IFR)
0.2-0.3% is by far in the bottom range of estimates
I think the data shows a pretty clear single order of magnitude difference between the IFR of the flu and novel corona. But I agree that >1% IFR is extremely unlikely