I expect part of the reason is so that when these episodes are repeated in four years time they won’t look too abnormal. Unlike Strictly or DOI shows like The Chase get repeated a lot.
I get that but at the same time, no one is going to forget this pandemic quickly, I think the impact on mental health will be longer lasting than the virus itself, so I'm sure if they ended up being repeated no one would be sitting going "WTF is going on?!"
At the very least, it would be an interesting bit of trivia that people might recall when watching the episodes.
Meanwhile, right now - I don't think it sends a very good message to the public, because whilst I don't count myself in their numbers, you can guarantee there will be people who watched that tonight and will go, well they're not social distancing so why should I bother.