It can be, if the procedure is the company's own and the employee's knowledge of it is advanced or uncommon within the company and the industry. Ordinary proficiency with standard aerospace quality systems that any trained inspector could match is not enough.
Distinguish the company's procedure from the industry standard
Aerospace quality standards are public, and every certified supplier follows them, so a claim built on knowing the standard will fail. The claim has to be about the shop's own way of meeting it: a fixture design, a data-capture step, a traceability database and the rules for using it. Hypothetical example: an East Hants process engineer wrote the shop's procedure over four years, trained six inspectors, and is the only person who can modify the underlying database. The petition should say so with dates, the manual he authored, and a statement from the shop explaining why implementing the procedure at the customer's plant needs him rather than a trained inspector. What usually goes wrong is a support letter full of adjectives — 'invaluable', 'unique' — with no documents behind them. A shorter letter with the manual, the training log and the database records attached is the stronger file.
Hypothetical example: an East Hants robotic-welding calibration specialist has developed the parameters used only in her employer's sensor array. A first review should make an evidence list: the controlled procedure, version history, training records, and a manager's explanation of why ordinary welding experience will not replace her. Those records establish the knowledge; the customer purchase order establishes the assignment. If the procedure is available in public manuals or the U.S. entity can train a new hire quickly, the company should reassess before presenting it as specialized.