In 1995, Duncan Steel, an astronomer then associated with the University of Adelaide, published an article in The Observatory speculating on the nature of this strange object, counting the likelihood that it was alien in origin. He noted that the fact that “none of the a few of man-made rocket bodies left in heliocentric orbits during the space age have purely gravitational orbits coming back to the Earth” Which means “it might be debated that 1991 VG is a candidate as an alien probe detected in the locality of our planet.”
Steel said “I do not think [VG 1991] is of extraterrestrial origin. I do think that we should take seriously the possibility that there are alien artefacts in the solar system, although I very much doubt that there are any, based on what we know so far.”
Scotti, in contrast, has not completely ruled out a natural origin for this unknown object. According to him, 1991 VG showed rare variations in brightness, which proposed that the object was spinning very quickly with just a few minutes from peak to peak. An astronomical (asteroid or something like that) object as small as 1991 VG, a rotation period of just a few minutes, while infrequent, is not completely impossible but very, very rare.
Scotti said “My question is where did 1991 VG come from and how did it get into its present orbit? One possibility would be that it is ejecta from a lunar impact. Another possibility is that the Yarkovsky force, caused by the thermal emissions of a rotating object, systematically pushed the object around over long times. It's still a puzzle!”
So the good thing is that we don’t have to wait very long to solve the mystery of 1991 VG. 1991 VG is once again making a close pass in the summer of 2017, but it will be far from Earth than in 1991 and only observable from the Southern Hemisphere.
One thing to be mentioned here (again), there’s always the chance that it’s a responsive alien probe, in which situation we should perhaps start getting prepared for the invasion.