Because to absorb someone's life is not what X-Men would do. It is the same as going back in time to when Mystique was a child and kill her, which was suggested by some idiot on some website. That would be a Magneto solution, not Prof X solution,

In the movies, Magneto has never shown the ability to influence blood. Yes, I am aware there is iron in blood. It is not like the comics are very consistent on that point. And anyone who obsesses about Kitty's time travel power must not have a very high IQ.

What is epic is your stupidity actually.

@ SuckuDungu. Do you know what the word "tension" means?

Don't understand the point about urgency at all. The clock was not determined by how long Kitty would last (altho of course if she did not, that would be the end of it), but by when the Sentinels would find them.