The old man that this post is about literally does have governing power, not only in the UK but also in 14 other countries including Australia and Canada. A common argument made by monarchists is that the monarch’s actual influence is negligible, and their governing power should be ignored because it is only ceremonial.
As Wikipedia puts it:
Royal assent is the method by which a monarch formally approves an act of the legislature, either directly or through an official acting on the monarch’s behalf. Under a modern constitutional monarchy, royal assent is considered little more than a formality. Even in nations such as the United Kingdom, Norway, the Netherlands, Liechtenstein and Monaco which still, in theory, permit their monarch to withhold assent to laws, the monarch almost never does so, except in a dire political emergency or on advice of government.