I got a lot of this back in the day. Even when I was going to meetings regularly, there was a family that would come to the grocery store where I was working. They'd rant on and on about my attendance right in the middle of my checkout line! The truth was that I had been going to meetings, but they just hadn't seen me there. It was a big congregation, nearly double the size of most, so that sort of thing happened a lot. They simply didn't believe me. Or maybe they didn't want to believe me.
Like, what the hell, man?
Another guy did the same thing when I was a teenager because I had just gotten baptized. He was nearly 30, but unbaptized, and offended that I was missing 2 Sundays a month to keep my job! Even though he missed more meetings than he attended. I pointed this out to him, and he agreed this was true. Yet, he told me, he wasn't baptized. And I was. So I had an obligation...in his eyes at least...that I wasn't living up to.
I had the same reaction to this one. By the time I had quit the KH, he wasn't even attending meetings anyway.
I could tell you lots of stories like these. My parents weren't Witnesses and opposed my going to meetings. So everyone thought they were entitled to be my parents in their stead. Can you say, "fun?" I couldn't.
There were lots of morons like these at my KH. Some of them honestly seemed to get off on it. I think it made them feel superior while also allowing them to nitpick someone to death. People tend to do this more in controlled environments like the KH. They get nitpicked by authority figures like the elders, so they find someone else lower in rank that they can pick on in turn.
The more casual indifference you show to this kind of behavior, the less of it you'll see. If you take it badly, you'll inflate their egos and encourage them. If you have a "so what" attitude and shrug at them, it will deflate their egos and make them feel foolish and nitpicky. Which is what they're being.