You say you change the (inexpensive) pump every 250 hours. That's my whole point. Your the one suggesting replacing parts on a pure time basis is in most cases totally pointless.
In fairness, he even under lines the "in most cases" bit. This to any reasonable reader indicates that he clearly has in mind some exceptions to his rule.
Replacing bits on a pure time basis is in most cases in fixed wing GA totally pointless.
Could you not see why he underlined that part?