[vacri]

Active versus passive is less of an issue here than a 'reasonable expectation of privacy'. Regardless of whether you're transmitting energy into a premises, you're still 'looking inside'.

It's worth noting that a normal human without engineering training is aware of silhouettes or even if the window is open - if they do things in plain view, there is onus on them. It takes specialised knowledge to even know this hi-tech stuff is possible for the most part, so you can't really equate passive collection of undetectable-by-human radiation to things like windows and silhouettes, when it comes to the average person.