Just so we're clear, he's not entirely wrong.

When the central bank 'buys' securities, they do so with money they're creating in that purchase. In effect they're dumping new money into wherever they're buying securities from, but the 'dumping' isn't with dump trucks or dropping it from planes.

Now those bonds come due and the money is supposed to leave the system, but until then the velocity of money means there are knock on effects.