For the case of Bayern, compare Rummenigge and Hoeness to Woodward. Consider that they can be afforded the luxury of appointing a relatively inexperienced individual at Sporting Director because of the wealth of experience in the organization both below that individual and, just as importantly, above that individual.
For the case of Ajax, again consider how long they've been operating with the organizational structure they currently have. The job of a DoF is not a new concept to them, and they have enough stability in place around the individual to be able to account for the lack of experience.
Now consider the role here. This position has never formally existed before. This person would be working with a relatively new coaching staff, a Frankenstein's monster group of players assembled by 4 managers previous to our existing one, and he'd have Matt Judge and Ed Woodward (2 former consultants and investment bankers by trade) as his superiors. Add in the ridiculous expectations of the job and two surging competitors in City and now Liverpool that we're expected to compete with. There is no nurturing bosom here to ease someone with no experience. Realistically, unless this person is hired to be a paper tiger, this person is going to be tasked with building up a structure from the ground up. That's why people want experience. For a position that's this challenging, with the lack of organizational structure currently in place, having experience with the job is sort of helpful. If that person wants to hire someone like Rio or Scholes or Phelan to work under them because of their institutional knowledge, that would make much more sense.