A friend told us of this scheme about a year ago. He said that basically any pre-tax money in IRAs or 401Ks isn’t really your money since you haven’t paid tax on it, they could decide to do whatever they want with it. Scary
On that logic, Roth IRAs are safe.
Unless you cancel the 401k and grab whatever cash you have. Soon there will be none. I would only leave matching funds and buy metal with the rest.