OxTox time is longer than NDL of ~5 minutes (by the tables that go that deep) and a bounce dive like that should be doable on an AL80, provided you're not hyperventilating from all the excitement. Gotta wonder what's down there to see in a couple of minutes, that was worth the risk, though.
I'm not worried about Oxtox at that depth diving air. There is some "evidence" that N² narcosis decreases the risk of a CNS hit.
I would be worried about breathing air that feels like breathing pudding at that depth (no matter the type or reg you are using), and hypercapnia. Specially in this scenario where there might have been a BCD malfunction, possible increased breathing rate, etc. In short not being able to ventilate the build up of CO², creating a dark narc, maybe panic. But this is all hypothesis.
What I do have experience with is the effects of gas density and hypercapnia on your narcosis level. Take a nice drift dive to 50m using air in the red sea and nothing will happen. Do that same dive but suddenly you need to fin as a madman against current (brothers isles for example) and suddenly the whole picture changes. Your lungs just can't overcome the effect of death space and gas density and cannot expel CO² sufficiently creating a vicious loopback where you are retaining more and more CO², feel more and more out of breath. But even before you feel out of breath your narcosis level will increase a lot. Same dive, different circumstances. This is fysiology and no experience or competence will change this.