I don't really understand how you understand it, but I suspect you aren't reading it right. But yes, gloves and tape will affect how everything will feel.

The difference in the effective top tubes is 580-578 = 2 mm. The difference between the two seat tube angles is 74 - 72.5 = 1.5 degrees. This difference placed the saddle 1.3 mm farther back from the BB on the new bike than on the old bike. The result is that the end of the top tube is 13 mm +2 mm farther back (i.e. closer to the BB) on the new bike than on the old bike.

To make the hip to BB position equal on both bikes, the saddle must be placed with 13 mm less setback on the new bike. The distance from the hip to the head tube axis is now 28 mm shorter on the new bike than on the old bike. To restore the handlebar to the same position it had on the old bike, the stem extension should be 28 mm (call it 3 centimeters) longer than on the old bike.