Whoever issued the bond, whether it's government or corporation, will get real spendable dollars when the bond is bought by a commercial bank. Those dollars are spent in the economy, which leads to rising prices. The amount of QE is pretty much equal to the amount of new money a commercial bank can create without increasing their risk.

Every bond is first bought by a commercial bank with new money (as deposits), and then the bond is bought by central bank with bank reserves. Equal amount of spendable deposits and bank reserves have been created. There are limits on how much bonds a commercial bank can hold, which limits their ability to create new money. With QE, they can swap the bonds into non-risky bank reserves which don't have those limits, and this allows them to create more money.

This is how I see it happening. The article is more nuanced, but I don't think it's accurate to say that QE doesn't increase spendable money in an economy.