If you force or attack the fairness system and receive two server seeds, one of them revealed, then the system no longer knows what result to give. It gets completely disrupted, and errors may occur, just like in any system that is breached.
You're saying the user hacked the site and was able to generate a server-side seed and take advantage of it. That sounds like the website's problem. Assuming the user a able to do that, why would the create a scam accusation rather take advantage of the broken system lol