Using lasers to hide the earth from aliens? Come on!

So I read an article about how scientists proposed using lasers to hide the earth from aliens. You see when a planet passes between an observer and its star the light from the star dims a tiny bit; this depends on the size of the planet, the size of the star, and orbital dynamics to name a few factors. This is called a transit and is one way scientists on earth go about finding planets orbiting other stars. Well these scientists have determined that using lasers they can mask the transit of the earth from being viewed from other star systems. Here is one problem I see that the article dead not address: every star has a spectral signature based on the chemical composition of the star which varies with size, age, etc. The light observed broken down into its spectrum will have absorption lines representing light wavelengths that corespondent to certain elements (read up on spectroscopy to learn more). To be effective the laser light would have to mimic the spectrograph of the sun exactly to be effective. This could be complicated due to the nature of laser light. So if during a transit an alien did not observe the dimming of the Suns light they would notice a change in spectrum and deduce there is probably a planet with a reasonably advanced society and something of interest. Better to let the transits be observed naturally so as not to show the earth is nothing but a planet orbiting a star and is of little interest. Let's call it "hiding in plain sight ."