I would recommend that you draw your SLO's attention to Section 203.2(b)(2) of the regulation (found on page C-1 of the Getting It Right guide), where preapproval programs are defined. I would also call his attention to the Official Staff Commentary on that section (found on page D-2 of the GIR Guide).
While he may not have intended to establish a formal preapproval program, it appears that his prequalification letters function like preapproval commitments. Whether or not you have ipso facto a formal program, I am not sure. However, I would respectfully suggest that revisiting the issue with the goal of clarity would be most beneficial.
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Management is doing things right; leadership is doing the right things. Peter Drucker