It was a hack, and it's very stable now,
One thing you should know is that, most of these p2p platforms go through some difficulties at first, Localmonero did, localbitcoins did and that's what made them stand strong before they shutdown after years.
OpenMonero has been running for 12 months only, so it doesn't make much sense to shut down a profitable platform and exit scam with barely $20k.
Regardless of whether or not the allegations that you rug pulled are true or not (your description is moderately convincing but that would obviously depend on who the hosting provider was), the fact that you lost basically the entire fund during the hack is bad for business.
Honestly, do you really think somebody would use a trading service if they knew that it was completely drained before, especially so recently?
Let's say it was another service, maybe KYCNAH or something. Would you trust such a site with your Monero?