Earlier quoted context omitted.
This is exactly the kind of inappropriate advice that the author is cautioning against. He was not just starting out, he had experienced teachers, and the horriffic panic-attack-like state he was not something that could have been addressed by "returning to the moment".
He was an instructor in "Mindfulness-Based Stress Reduction" -- sorry, this is not a real thing. He's been teaching things he clearly does not understand, and his mind was blown by this. When I say "a teacher would tell you to come back to the moment" it's not quite as simple as I make it sound, the key thing is who the advice is coming from (read: an actual zen teacher who has received transmission, not a charlatan…
Why Zen specifically? There are many different types of Buddhism.
Even if it does have to be Zen, which kind of Zen? Rinzai or Soto, or some mix of the two (which some Zen schools advocate)?
And why Buddhism, anyway? Meditation is practiced in many different religious traditions.
"mindfulness" is itself rooted in the Theraveda -- not Zen -- Buddhist tradition, but that doesn't necessarily mean that the "right" way to meditate must be a Buddhist way as opposed to, say, one of the many Hindu forms of meditation.