I've looked up some papers on the maximum incubation period (by no means a comprehensive search):

- https://pubmed.ncbi.nlm.nih.gov/32594928/ (14 days in 99.5)

- https://academic.oup.com/ije/article/doi/10.1093/ije/dyaa106... (this one says 95% within 14 days)

- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7302302/ (preprint, says median is 5.35 days, and says the data support the 14 day intervention policy but gives no data about why so)

Most of the studies are with "old" outbreaks so likely more data is needed. Yet the median is still around 2-6 days.

> Playing it safe with the incubation time

That is, applying the precautionary principle. Not very scientific, but understandable (although I don't agree with it). Personally, now that we're well into the epidemic, I'd expect a little more rigor, though.