To my eyes, this cable confirms what the Politico article said. It says there is a "serious shortage of appropriately trained technicians and investigators needed to safely operate this high-containment laboratory". This is on Page 2, in the last paragraph. As for what's dangerous, Page 3 specifically mentions research undertaken with funding from NIH/NIAID studying SARS-like coronaviruses that can interact with ACE2 (transmittable to humans). Handling such viruses, particularly ones whose infectiousness has been increased (gain of function), in a lab without properly trained staff, seems pretty alarming to me.