Problem with the theory is that Poloniex is a US company. In the US how a catastrophic loss of funds works at a business is as follows:

• They announce they have been hacked, and disclose funds were lost
• They either go bankrupt or they survive

The reason people in the US generally go that route is that if they did what you suggest, they would go to jail. To avoid jail time in the US, it's easier to just go bankrupt. The management and ownership can keep their big salaries and dividends and stay out of jail.

So it does happen in the US that businesses commit fraud, but really, these people never are thinking straight. It's simpler to go bankrupt which is basically like a gimme for a business. Sometimes they're allowed to restructure even. Sometimes if it was theft and they were insured, insurance could cover the loss.