Being a mutant with incredible telekinetic and telepathic abilities, he grew up to be incredibly strong (taking on the name Cable), and eventually time traveled to the past in order to try and right the world and prevent a horrific future.
Cable is a character who possesses one of the most complicated backstories in all of Marvel Comics.
Now that we know he’s come back to our time in Deadpool 2 to put a stop to a young mutant, it’s possible that the child leads to the very future Cable is desperate to change.
With no other options available to save the baby (named Nathan Summers), it was agreed that he would be sent to the future where a cure was available.