Yes, the report remains open.

I was a mod till about a week ago. When I responded to a report of someone commenting something like "DUPED" or "lol lowball", and the trade owner had already hidden it, I'd just close the report most of the time, because my normal action would have been to hide it too. They still get looked at, but if you plan on hiding it and it's simple spam, don't bother reporting it, because you've already done all that they would have.

oh ok, i just consider it defacing my post, the guy wanted full tf price and i hid his post, and he came back to complain as if i were obligated to buy it from him, really annoying behavior.

Just hide him again, unless it becomes incessant. The last thing we need is 500 reports saying "He's lowballing/highballing". (Although, we actually already get that.)