Actually, I'm in full agreement with Dave Davis. The sudden shift may have been due to the very question of why not use a gun?
Again, you're still dealing with a very small target to hit. That ROUND (not wide like a knife) stilletto has to hit a very special place , and be deep enough. The only thing that could duplicate that, really, is an impressive jab with a pen, or a very good shot.
There's a fact that many audience members overlook (that *might* apply here. I have no real idea if it does, the following about Mulder & co is supposition), but that writers seldom do: Characters react to what they know.
The reason writers seldom overlook this is not because of hoity toity, we're better than you...it's because, as a writer, that's HOW YOU WRITE CHARACTERS. That's all.
Mulder was reacting to what he knew. It was important. It was a known way to kill the bounty hunters, where shooting them didn't work and could cause toxic fumes. Shooting him in the back of the neck may work, but he didn't know. Maybe there WAS something special, an alloy or a third agent in the "needle". It was important, and he had to get it.
Maybe Scully, in her pragnatism, just tried shooting, hoping it would work.
Maybe it was just bad writing. But contextually, it fits how both characters tend to think. Does that mean that's what the writers intended? Hell, I don't know. I'm just doing continuity forensics. The evidence suggests a probability, but we're missing key evidence to determine the validity of the hypothesis: the writers.
Lack of sleep + forensics degree makes Jack a wordy git. Sorry
