Alito voted not to vacate the lower court’s ruling. That is hardly the same thing as being anti-death penalty.
It simply means that he didn’t see enough evidence presented to warrant vacating a lower court ruling.
Besides - the vote tally I heard was 6-3. His vote means nothing if it is a 6-3 decision.
But it certainly makes good fodder for the out-of-control instant news cycle rags.