there's a major error in their calculation in that they didn't do that in 3 dimensions, and they assumed that all planets always lie on the same radius from the sun. do the math again with jupiter and saturn on opposite sides and use 3 dimensions, and the CoM should go back into the sun.
Also, Jupiter and Saturn make up most of the mass of the planets (1.8986×10^27 kg and 5.6846×10^26 = 2.46x10^27) where the total mass of the planets is 2.67×10^27 kg.
As long as Jupiter and Saturn are aligned with the sun the barometric center of the solar system will be outside of the sun, and they would align once every 12 years or so, so this does happen from time to time.
