I think the point is that alexa is actively scanning the network for that information, which begs the question what else is it scanning for, or might in a future automatic update?
Fair enough. It would be prudent to assume that your Alexa is actively looking for whatever open information is supplied by devices on your network, especially information that has been announced as being supported by Amazon[1].
[1] https://www.amazon.com/b?ie=UTF8&node=19820259011