No, you really aren't lost at all.
He doesn't play kids, because he CHOOSES not to. Not because it's an unacceptable risk or because they are all weaklings or because they are no good, or 'not ready'. He weighs up playing a cb or frank Lampard at cf & thinks 'nah, I'll chuck Pozo in' On another day, he thinks 'shall I bring in Maffeo & give him 20 mins to rest Sagna at the end, with Zabba being out' thinks nah fuckit, I'll gamble on sagna.
It's a 'choice' he makes when he weighs up the pros & cons, not some unwritten rule of 'compromising the team' which all these bullshit artists are feeding us.
The kids don't play, because he chooses to pick the older players because he prefers them.