That bit of plot made less than zero sense, by the way. Why is Mystique's DNA more important than any other mutant? Adaptability wasn't even her mutation, she's a shape-shifter. We saw a mutant with the "adaptability" gene in First Class and he lasted about 3 minutes. So I'm calling bullshit on the whole "shape-shifter DNA results in robots that adapt," right there. Shape-shifter DNA should result in robots that shape-shift. And it's not like you want the robots to be able to shape-shift; they're huge, fuck off scary monsters. They don't need to shape-shift into something less terrifying.
If you were going to distill a mutation from DNA, wouldn't you want something like Xavier's ability to read and control minds? Hell, X2 already showed us that if Xavier just concentrates really hard in Cerebro, he can kill every mutant on Earth simultaneously; that's a MUCH more useful power to give your mutant kill-bots than shape-shifting. You could wipe out the entire mutant problem in an afternoon and you wouldn't even need to leave your office. Or give them Magneto's power, since he seems able to beat all the X-Men singlehandedly every single damn time he turns up. At no point did the "Mystique's DNA is the most important thing in the world" storyline make a lick of sense. "Yeah, what we're really looking for in a robot is to be blue and limber." Fuck that.