Eh. The funds are actually held at Vanguard, so you could easily roll this over to them upon failure of Guideline (or even before). This all comes down to what your small employer can do.
Just want to be clear the funds are actually held at the custodian, not at Vanguard. That's why it is super important to have a well established Custodian. You can always rollover your funds in a qualified event to another employee sponsored plan or an IRA. BTW you can do that with most publicly traded funds, and you could also do a cash balance transfer.