The characteristics of scorpions varies with specimens. Some are mellow, some are skittish and will run for hide at the slightest disturbance but some will stand on their ground to defend themselves from perceived danger.
I would think that your scorpions react this way (lunging at the tongs) is simply a sign of territorial defensive nature. He/she has established a familiarity in his surroundings and hence will prefer to be left alone and will defend his ground readily. If you ask me, i prefer that my scorpions react defensively with such vibrant of life then to react motionlessly when i'm near them. Of course, do not disturb them on purpose. Once in a while (e.g. if it happens once every 2-4 weeks during tank maintenance etc) is not considered stressing them out too much. However, opening up their hide daily and handling them, is.
Cody is right that they will get to the crickets if they are hungry. If you do not wish to leave crickets hanging around the tank and possibly risk of them dieing in a isolated spot, attracting mites in the process or having risks of them attacking a molting scorpion. You may continue to tong feed your scorpions but just hold at the entrance of the burrow/hide. They will take it if they're hungry, else try a week later.
