I can usually come up with some bit of lateral thinking that would explain things, at least is someone's universe, but not for this.
Since the crew had selected the gear down early and declined ATC help suggests to me that they were indeed comfortable with their position. I wonder if they had done similar types of approach before? If the gear had remained down at the 5 mile point then perhaps we wouldn't be having this discussion and PIA's lack of data monitoring would have gone unnoticed for a lot longer. (see post 12 of "PIA banned from Europe" which shows EASA reason for the ban).
I suspect the gear was raised in error at 5 miles because PF normally called for gear at that point (learned reflex) and the PNF normally moved the gear lever. When the aircraft ceased to decelerate as expected, then confusion overloaded their last brain cell.
I'll wait for the CVR and accident report with interest.