The other thing for this example in particular is that cruise missile technology goes back decades. The Tomahawk was originally built with the finest of (disposable) late 1970s microprocessors. You just don't need a lot of computing power to run "fly this preprogrammed course and explode at this GPS point" or "fly this course and activate your radar after 15 minutes, then fly into a target that looks like X on your radar."

So the idea that a 2010s appliance would have chips powerful enough to run a missile seems plausible.