The fact is that any conventional 30-meter telescope can resolve an earth-size object within 30 light-years (circa 6000Angstrom in wavelength). Spatial resolution can be determined by the ratio of wavelength to diameter of the optics:
6000A / 30m ~ 2e-8 radian ~ 0.004 arcsec.
So a 30m telescope can resolve an object in angular size of 0.004arcsec at 6000Angstrom.
At the distance of 30 light-years, the earth-size object looks like
6400km / 30lyr ~ 2e-8 radian ~ 0.004 arcsec.
So that's that. This telescope doesn't give us any special resolving power per optics size. So the advantage is merely its light weight.
Since the precise alignment of holes is required for this optics to work, I can see why this project got kicked out by ESA. It's probably too premature to attempt in deploying this kind of precision engineering in space today.