BOG-MIA is a short sector, typically 3:15, so the airplane weight wouldn't have been critical on 3 engines at 10,000' MSL, or 1,600 AGL.
From memory, typical max ZFW on the Classic would be about 267 [Kgs]; add to that about 60 tons for the fuel and it would make the TOW only 327. MTOW on the Classic [at sea level] is 377+ Kgs. Given the high cost of fuel, it's dubious that they would have uplifted more than minimum required fuel.
The airplane was airborne, in climb mode, so something more must have been at stake than just one engine failure.
