Let me play Devil's Advocate for a moment - suppose plan accepts loan payments by check? (some do) - or suppose this person was they payroll person, and doctored the accounting somehow so that embezzled funds were run through payroll as a normal loan payment? Doesn't seem like any plan operational error there to me.
The loans were repaid though with real money, and they were applied to a real obligation. It is where she got the funds that presents the problem.
I'm not suggesting that the courts can't garnish the money, I actually have no idea if they can. I'm merely saying the plan did nothing wrong here and there is no operational failure to correct.