Quite the superfluous vernacular which in the end has absolutely no benefit towards anyone who speaks normally.
I have never met a health professional that speaks this way to clients, and it is actually a tell tale sign that they indeed have no real world experience.
"I feel that pathologising a minor and completely asymptomatic anatomical variance in bone structure due to either congenital or developmental causes is a waste of time and resources - for the individual who has been pathologised and has to pay for treatment out of fear of these 'future' problems."
asymptomatic anatomical variance... wow. I'll leave it at that.
OP, what this guy is trying to say, in the most bizarre way, is that it is unnecessary to treat imbalances incurred from your lifting. I would say thousands of chiropractors, corrective exercise specialists, masseuse, and physical therapists would disagree... especially these days with the emphasis on preventative medicine.
He also recommends that you wait for pain to actually do something about it. I equate that to telling someone to keep drinking whiskey until they start getting liver pain.
And to pgtips
"It's a big jump and actually quite unprofessional to come to those conclusions and suggest an almost definite road to pain and injury by looking at a couple of static photos without taking a thourough subjective/medical history and without even a full physical assessment of this chap - who has absolutely no symptoms apart from a largely unnoticeable (unless looked for) aesthetic niggle."
If you're curious enough, print out the kids photo and show it to a licensed chiro (not a physio,or pt). They'll be able to deduce many things, even how his squat might look. Of course having the client in person is ideal, but we have to be able to prospect a list of things even before we work on them.
No need to be worried. As many have already mentioned, being asymmetrical is inevitable, and at times can even be advantageous (take that with a grain of salt). You're not gonna die or break your back. But part of injury prevention is keeping ourselves closer to symmetrical than asymmetrical, especially the spine.
What can you do now? Just be aware of it. Perhaps you feel more tightness on your left side when you squat or deadlift. Your balance is probably better on your left side too. Things like that. I would highly suggest you see a chiro and if you do, keep us posted.