Why would aliens be interested in our Nuclear silos?
Same reason some people are interested in obsolete antique weapons. Or ... They are amazed that we were stupid enough to test and use them on our own planet instead of in space or on the moon.
Any alien species advanced enough to travel here would not be interested, they would be sufficiently advanced such that they could do as they pleased and we could not stop them.
You don't know! If is was coming here from and advanced world, I would want to know what kind of weapons there are and how many, and how they are controlled. The best way to achieve this would be to visit the sights where weapons are kept, and nuclear plants with breeder reactors that make the fuel used in them.
Nuclear science is the first step before serious space travel. Controlled fusion is probably needed to travel in deep space. Aliens are checking the state of nuclear mastery (which is not very advanced) to evaluate: why we are stuck with bombs and fission, how long will it take to build advanced nuclear engines, a general evaluation of technologies and organization. As soon as men travel into deep space, man may be a potential 'threat' to other space civilizations.
They wouldn't. If they needed weapons against our planet, they'd just adjust the orbit of some suitably sized asteroid to make it hit Earth.
