Yes, I agree you can correct the HUD before or at closing, and send a corrected HUD when an error is found. However, sending the corrected HUD, after the fact, does not shield you from any liability that may or could be imposed.
The following is taken from Kirchmanís Q& A on RESPA:
Q-20. If we find errors in our RESPA disclosure to a Customer, can we correct them within a certain time and escape liability the way we can under Truth in Lending and Truth is Saving?
A-20. Only as to the Servicing Transfer Disclosure Statement. It is covered by a specific correction procedure similar to those in TILA and TISA. None of the other RESPA disclosures have such a provision in their portions of the statute of the regulation. We confirmed this situation with HUD. RESPA, section 6 and Regulation X, section 3500.21(f)(2). (It is still good practice, we believe, to give corrected disclosures, though.)
The opinions expressed are mine and they are not to be taken as legal advice.