The expression “non-white-haired” means young.
The author of the article was trying to show-off by using a simile, idiom or something ... but the end result sounds quite clumsy. It's worth noting that it's more common to write “silver-haired” when (perhaps humorously) referring to the elderly demographic.
Note that the word “set” (basically meaning crowd or group) is often used idiomatically in such a sentence, again in an attempt at mild humour by article writers:
"I want to find an App that is not targeted at the pre-pubescent set!"
"The Tonies are finally aiming at an audience other than the nursing
home set!"
Note that using a "non-" in combination with a humorous or extreme thing, generally, is one of these ‘tricks’ that magazine writers think adds to their writing. A kind of sarcasm. So you'll often see things like: “Finally, a sports car for the non-billionaire set!” or “At last, an app that can be used by non-PhDs!”
1) It's one of these supposedly humorous uses of "non-"
2) Silver-haired means ‘old folks’. For me the "white" is basically a typo, if I were the editor I would just change it with no comment to silver-haired
3) Note that typically "set" is used when referring, perhaps humorously, to a demographic - often used with a sarcastic object thing before the "set". ("this beer is so cheap it's only for the 'Animal House' set!" "This song will only sell to the Neil Sedaka set!")
4) One final point on silver-hairs. Much older women are sometimes referred to as the “blue-rinse set” .
Just BTW, you see how I'm criticising the writer in question as "trying to be funny". The passage is packed with stuff like that. For example, “high-octave” is a clever play on high-octane {assuming it's not just a typo}. So, that's the deal.
