By making intrusive surveillance devices available inexpensively (perhaps by showing hobbyists how to build their own), such devices could move (as planes have) into "general public use" and then be usable by police without a warrant to surveil areas normally off-limits to them without a warrant.
I cannot fault your analysis of that particular sentence since I'm certain that some lawyer somewhere will eventually argue that when the "not in general public use" criterion is absent it somehow becomes a "reasonable" search.
On the other hand, simply because a technology becomes available to monitor something formerly private does not mean that that technology will stay available and become something in "general public use." The now classic evolution-begets-prohibition example is radio frequency scanners. Making or using scanners to listen to analog phone transmissions for fun or profit became a bad idea, not something in general public use.
If you consider that merely listening to something that people voluntarily broadcast, in the clear, was deemed illegal, what do you think the reaction is going to be to your nosy neighbor bathing your home in artificial radiation for the purpose of peeping at things going on that are not ordinarily visible from the outside? That everyone will accept that shielding their home is impractical and simply shrug? Not once some git uses the technology to surveil a politician it won't.