Block 1As have autonomous IR mode in case the target isn't emitting. It's the more numerous Block 0s that are RF/IR only, heading out on a RF bearing line and switch to IR for the terminal phase.

And FYI, CIWS has been upgraded: it's now "Captain, It Works Sometimes". Combined with the improvements in the "Ain't Ever Gonna Intercept Shit" and "Random Ass Misfires" systems, the US Navy is well-prepared to face any upcoming ASCM threat.