Once the electricity from the lighting strike got into the aircraft, it too became an internal source. How else did it get inside the fuel tank?
NTSB reproduced this at least twice. Once when they were trying to do it in the first place and once when they were measuring potential damage. There are numerous references to other fuel tank explosions on this thread. Read them and also read the NTSB report.
I disagree with you guys that all the eyewitnesses thought that a burning airplane looks like a missile, flare, or fireworks. IMO, a kerosene fire does not look like a missile, flare or fireworks, which give off a much brighter, more intense kind of light. It's just not plausible that all the witnesses are wrong. The CIA's preposterous simulation showing the plane making a huge climb after a massive explosion is much less plausible than the eyewitness accounts of a missile, flare, or fireworks.
I've seen no evidence of mass hysteria or people just seeking attention and I've read a lot of the testimony. A modified shoulder-fired missile with extended range could have reached that airplane at 13,700 feet of altitude. Heck, even Rokke agrees on that point. A group with extensive financial resources and technical knowledge would not have difficulty developing a missile that could reach an airplane at that altitude.