Ideally it would have been postponed but that's not simple either. Where do you fit it in? One team or the other would no doubt be moaning about the rescheduled game because they ended up with a day or two less rest than their next opponents. Plus, I would think the authorities are shitting their pants in case any of the games end up having to be cancelled due to covid outbreaks within certain teams.
In an ideal world there would only be one logical decision but we don't live in an ideal world.
Also, I hate to be cynical and I'm not for one minute minimising what the Danish players went through (it was upsetting enough just for us sitting at home) but I can't help but think that we wouldn't be having this conversation if the Danes hadn't lost.