The Part 107 remote pilot certification is an obvious need for business but going as far as getting a PPL is not legally needed
I'm just playing devil's advocate here, "as if" I was an IRS auditor. No response is really necessary. Just providing what I guess you would call "food for thought".
On your threefold justification, if at least one of the three are not a requirement of employment or continued employment, I (as an IRS auditor) would disallow the deduction.
Additionally, while training/education for maintaining or improving existing job skills can be deductible as a business expense, such training/education for new job skills is not. See IRS Topic 513 at https://www.irs.gov/taxtopics/tc513
Note that just because an education expense may not be deductible as a business expense, does not mean you can't claim it as an education expense if it meets the requirements to be claimed as such. I don't know if schooling for PPL meets the criteria as an education expenses or not. But just off the top of my head I would not expect it to.
