[bumby]

I think there are still mechanics at play that would have to be considered.

>The probe bears on the ice below it

This implies it is bearing the weight of the entire cable above it. So instead of the tensile stress being the limiting factor, it's not the compressive stress. If you're intent is to retract the spool, it would still be in tensile stress as it comes up. (And you'd need enough torque to do so. But maybe you the plan would be to abandon in place).

>What you have to worry about is the ice shifting and severing the cable.

I agree, that's a pretty big concern.