It's very possible that this hit was closer to the computer than was assumed
it it logical to say that a lightning hit on an aerial pair would have fused the line, shunted mostly to ground, and been partly absorbed by the carbons/mov's in the premises. A powerful hit (which this obviously was) might have struck the power wiring, and very likely have generated a surge in nearby phone lines - the affect might have been even worse if it had hit LAN wiring.
I have seen many lightning hits in my career and can only say that voltage of that magnitude pretty much goes where it damn well pleases!