Um, because part 61 evaluations lack consistency and credibility, the DPE cottage industry they feed is a stain on the industry, and ultimately they matter the square root of eff-all to military accessions. That's how. The OP is self-evidence of this fact.

If the Delta-of-the-week wants to shun him over part 61 effetry during college, that's life. You can't change the past, no sense in having to feign contrition over it. If they think you're a PR liability, no amount of mea culpa is gonna change that. Die with your boots on type of thing. With his pedigree, plenty of money to be made outside the airlines. And as rickair777 already highlighted, it's not at all a given that other six-figure income employers would disqualify him outright over part 61 nothingburgers as a mil applicant.