Your first powder experience shouldn't be in "bottomless." Try six inches or so. That's enough to feel a little bit of the floating sensation of powder, the sensation of being "in it," rather than "on it," and of standing against the whole base of the ski, rather than just the edges, even when they're tipped. It's enough to taste the slowness, and the quietness, of powder, and to learn to ski it with rhythmic turns less compete than you'd use on the same slope without powder.
And it's not so much as to overwhelm with new sensations and challenges. There's still a solid base to support you if you lose your balance. If you get nervous, you can still usually twist the skis sideways and brake to a stop if you have to, although it's enough to show why you don't often want to do that in powder!
Start small. Gain confidence. Get used to the sensations.
THEN hire the helicopter!
Happy New Year!
PS--all of the above assumes that the skier does, in fact, have "decent technique" and tactics in the first place. Many skiers new to powder find that the condition reveals flaws and errors that they didn't know they had. Almost anything "works" on groomed snow. Great powder skiing--like great technique almost anywhere--relies on the skis going the direction they're pointing (as a habit), rather than skidding sideways to brake.
If it's not already a habit, my first advice for powder is to focus on making your skis go the direction they're pointed. And if that doesn't work, point them the direction they're going!
(Ironically, almost anything works in deep, light powder, too, once you get used to it. It's really one of the easiest conditions to ski. Poor, upper-body-rotation-based technique can huck the skis sideways quite effectively in light enough snow, especially with today's big fat powder boards. One sign of a technique that could use improvement is the inability to enjoy powder on both narrow skis and wide!)