I've never had an examiner object to "the bank does not offer" as a denial reason (or objected to it when I was an examiner), as long as it was true. If you don't offer the product, you don't offer the product. In your situation you may want to specify that you don't offer 15 year term but you do offer 3 year terms. "Doesn't fit bank policy" is too vague as you would need to specify what bank policy (LTV, collateral, etc.).
Others may have different experiences and advice, but I don’t have any problem defending “bank doesn’t offer” as a denial reason (although it is often used incorrectly, which is a different situation).
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Where I go there I am.