Looking back on it now, did he see something the others didn't?
Let's again, in theory, put aside his mean streak for these past few years. He'd been made to look like the big bad guy all through the whole picture. But, if he had gotten his way, would things have been different for Homo Sapiens Superior? We kept hearing that Hope was going to save them all, but has she really? We kept hearing that Cable would trust in Scott to know what to do when the time came. Well let's say, perhaps Cable should not have done what was possible to see Hope lived from this supposedly accidental killing by the Avengers in the future, and just let unchanged fate take its course. Perhaps, Cable was wrong?
We seen possible futures, not set ones after all.