There is no prompt to ignite Winona's GEMerator with a torch, even though it is flammable. The prompt appears with a Fire Staff equipped, and it appears for the torch on other flammable structures. The GEMerator can still smolder and ignite from nearby fires. Only the specific GEMerator/torch combo is barred.
Winona's nitre generator is unaffected, and can be ignited with a torch normally.
1) equip a torch, or hover a torch over Winona's GEMerator with your cursor 2) observe that no "Light" prompt appears