True, but I don't see here (albeit without much to go on) a case for blaming the training, either.
I do remember in my own PA28 140 ab initio work in Moresby, yonks ago, dumping flap in a go-around was absolute anathema.
(The littlest Cherokee never seemed to have trouble climbing away, 2-up, full flap, despite the heat and the humidity.)
To dump flap is to dump lift, was the mantra. The lever had to be left where it was until a positive rate - on runway heading - was established and then, ever so gently, progressively eased off.
So if this young chap's training was anything like mine, flap dumping would've been the last thing to have 'kicked in', as they say.
Actually, I remember doing just that once, on a go around with an instructor who, as our climb-slope sagged alarmingly, went apoplectic, saying I'd get us killed doing that.
On reflection, I realised I'd done it reflexively; the imprint of all that touch-and-go practice, where you usually do need to dump landing-flap quick-smart before powering up again.