Well I would hope the auditors to have common sense. But we auditors are notoriously hard to calibrate, so we should take care not to confuse lack of alignment with silliness.
17025's elements mirror 9001 requirements in most cases, so I don't see why a 17025 qualified auditor can't at least help out with 9001 audits. I would consider taking advantage of this person's strengths, so auditing calibration seems like an obvious choice but maybe Design should be dome by someone more familiar with Engineering.