Metal in his blood? I doubt Magneto would need to use the " metal in his blood " seeing as how that HALF of his body is MADE of metal. In Fatal ATTRACTIONS #25 he merely blinked and ripped Nathan in half. But -- since he does have greater powers now I doubt that could happen. Nathan is an expert at holding his body together. His telekinesis is UNMATCHED. I'm sure it wouldn't take much effort to stablize his own body before Magneto had the chance to pull him apart. And by then Cable's telepathy would either A. Kill Magneto instantly. Or B. Shut off the section of his brain which allows him to execute his magnetic abilities. ( Yes. He can do that gentlemen. )
Magneto on the other hand could rely on other stand points rather than the easily traveled road that MOST take. For one Magneto controls gravity. I mean if the man can control the Magnetic Polarities of the entire PLANET I'm sure he could enforce great weight upon Cable making him immobile. A lot of GOOD that would do but -- it's a possibility. And I'm not sure if Magneto is very telepathic. He's always displayed some resistance but again not much. But if he could short out Cable's mind with a few eletrical shocks. He might win. Electricity and Magnetics are very close.