Of course, but - as above - context is everything.
ShortWarning (apologies, buddy!) was squatting with a belt to prevent further injury. This indicates his form is less than optimal and - if it isn't what caused his back pain - certainly won't be helping. The use of a belt in such circumstances suggests that - whilst he's very strong for his weight - he's not necessarily an "experienced" lifter in this regard. Also, being slated for an MRI emphasises that his doctor isn't certain what's going on, either.
I'd actually have suggested going to see a physio instead of a doctor, because medical practitioners receive very little training in how the musculoskeletal system works together.
@ShortWarning: sorry for not answering this before, but the point at which a person starts wearing a belt for any benefit is when reps/sets get so heavy/prolonged that your form starts breaking down. Now there are two sides to this:
1) it means you can maintain "form" for longer and keep the volume levels up.
2) you aren't bracing *optimally* because you're bracing
against something (the belt), so - typically - this means your ultimate weight squats/deads will not have optimal form. Whether or not this matters to you is entirely a point of perspective. I've never worn a belt and have no intention of doing so because I'm not a competitive powerlifer or (sob) weightlifter.
An interesting side-effect of point 2 means that - if your form DOES go whilst squatting with a belt - there is a reasonable chance your injury will be worse because your muscles can't attenuate the shear stresses as they normally would (as you're using the belt for support).
Does any of this matter? Not really: some people choose to wear a belt because of the mechanical advantages it can provide if used properly; I don't because I know I don't train in a way that would benefit from what I perceive are the compromises.