completely agree, and commented on the thread you're talking about.
It's so weird, it wouldn't even cross my mind to query why someone is in work.
It's like some posters are still stuck in 1955 and everyone gets up and goes to the office for 9am on a Monday and finishes at 5pm on Friday.
People work part time, work shifts, do condensed working, take annual leave, accrue toil, work 'on call' (so have to be available but not actually working), can be on maternity leave, on sick leave, work for themselves, work freelance etc...
Tbh even with my job, which is a traditional office based (except I now mainly wfh), one where the public opening hours are 9-5, my role is so flexible that I could absolutely be working today but take 2 hours off to watch tv or whatever the OP was doing, with no issue at all, I'd just make up the hours later on in the day/week/month.
And even if people don't work for whatever reason, it's very rare that this actually has any relevance to the post. Even if the OP was hitting all the Daily Mail "workshy benefit claimer" tickboxes it's got nothing to do with the question asked (in that case about a row with a husband!), so why the need to even query it?
also agree with @Mooozer, "early birds" are particularly judgey of nightowls as if it's a character defect to not be working by 9am.