If the TPA is enrolled in some manner covered by Circular 230 he/she/they cannot prepare the form with knowingly false information without risking enrollment and other sanctions as outlined, you can read it for yourself.
Even if not formally covered by 230, it's a good guideline for standards of practice. If the TPA has already been paid to prepare the 5500, they should do so with correct information as they understand it and send it to the client, client can choose to file it or not. Alternatively resign and possibly refund any pre-paid fee. If the TPA hasn't been paid and the client doesn't have money to pay the TPA, best just to resign. There is just not enough profit in any one administration engagement to justify a TPA knowingly preparing an incorrect return. If/when the SHTF the client will come back and blame the TPA for doing so.