Force is commonly measured in foot-pounds per second; 60 MPH is about 88FPS and 9000 turns into 19,360 just for the brick.
Had the author used 40 MPH (roughly 60 FPS) his math table would be logical but the rest of the article and the rest of the math, especially that which compared speeds based on mass would still be wrong.
Some people can't be trusted with a spreadsheet; GIGO.
Thanks for checking; I didn't. I assumed that the higher mass of the vehicle would result in a greater force-on-impact for an equivalent speed compared to a lighter vehicle (it should, of course), so I took it for granted that the author had done the math correctly. I'm not going to do the analysis myself, but it would be interesting to see accurate numbers on this.