I think you're missing the point
Actually he has a very good point. The article is wrong: there is just as much mass "beneath your feet" since technically the entire planet is beneath your feet. The point is that the mass is, on average, located further from your feet near a mountain because of the thick crust which floats on, and displaces, the far denser mantle. The gravitational field depends not just on the mass but on the distance as well.
What I don't understand is how this counts as 'news'. The effect was discovered by the British Trigonometric Survey of India where they noticed a discrepancy in their measurements caused by the fact that the 'vertical' was not the same near the Himalayas. This was well over 100 years ago...hardly news.