You accept answer based on merit. What answer you feel has answered your question completely should be considered accepted. See: astronomy.stackexchange.com/help/accepted-answer

I am getting very suspicious vibes from that person, now that they deleted that physics SE account.

That would be correct but the behavior is repetitive. I see that person has deleted their account three times this year. In every posts, there has been some comments about the deletion. Today, that person created a new profile and asked a question. Some more details in the OP comment section...

The user has deleted their account on September right after posting a question and today, that person created a new profile and asked a question. I looked out in other SE sites if we see this profile and what do you know, this user is banned in Phy.SE. Curiously, the profile is 17 days old and there is no posts, yet the account is banned. Food for thought?

I am quite careful with raising flags, but if you say I accidently flagged the question instead of the answer, then it must be a mistake from my part (probably less coffee). And, yes there is no harm done. Just a small query from my side. Cheers!

I was one of the few user who took initiative in fixing the old posts. Here is one example where I removed the markup "doesn't exist" because there was already a video linked to the answer and I assumed the screenshot were from the video, so I removed them. In this case, I didn't knew what is the image and what image it could replace with. So, it was left as it is.