Or put more generally, "Why would they care?" We'd have nothing a vastly more advanced civilization would particularly want from us, and we'd pose absolutely no threat to them.

If they are crazy genocidal monsters wiping out all intelligent life besides their own, then they're probably systematically looking for targets, sending out their own probes to check out any planet that could sustain life. If they have any kind of presence in Alpha Centauri that could detect these probes, then they'd be here soon enough even if we didn't send out a probe.