Morning @Tulipomania and others.
Just in case it gives you a bit more background, am afraid I don't know anything about the specific thread you're talking about, but sometimes what will happen when we get a report is this:
It will look like the thread does need looking into but we know that might take a while, so we'll reply and say 'thank you and we'll look into it' just so you know we've seen the report and are onto it.
With threads like the one you're talking about it might be that we can see exactly why you've had suspicions but we can't see anything concrete at that point to make us think the OP isn't genuine. Or maybe they're asking for help and we feel it would be worth giving them the benefit of the doubt and see how things shake out. Then, possibly days later, more evidence appears, or the thread jumps the shark or the troll otherwise gives themselves away and so we'll delete it. Of course, most of the time, if you hear nothing more it's because we've had a look and are pretty confident it's all fine.
Honestly, if we had the time, we'd love to go back at that stage and follow up on mails - talking to Mumsnetters genuinely is the best part of the job - there just is rarely the time to do that, sadly. And we don't like to give too much away on the thread deletions as that just helps the trolls out. So that's why it occasionally looks like a bit of a mystery.
You can always drop us a line though if you're curious about a particular thread and if we have any more info we can share, we're happy to do that. Nine times out of ten though, it's a straight case of 'weren't sure it was a troll. Once we were sure, we deleted the thread'.
Hope that helps explain it a bit further anyway.