Non customer Joe Blow presents on-us $11,000 check and wants $11,000 cash. Joe volunteers that he is a car salesman, owns Joe Blow Motors, and the check is payment for a sale. So the teller logs occupation as car salesman, and DBA "Joe Blow Motors" in box 5 (legacy form). But staff in the bank want me to remove the DBA information saying it's not our business. I say it makes the bank look bad for cashing a check that should have been deposited in his own bank account. Their reasoning is that he possibly wanted to ensure he got the $$ making sure the check was good. What are my compliance issues if I leave the DBA information in block 5 - or not? Or am I being too worrisome?

While I agree that it makes the check cashing decision look bad, it's what you actually did so the reflection is somewhat accurate. For BSA purposes, there is no need to leave out a piece of requested information that you actually have. It could be an issue if you leave it out, but not if you leave it in.