Yeah this is a fairly poor article by an otherwise amazing blogger.

With that said the point stands that the likelihood of sending bitcoin to an unintended address due to a typo is very small. It's not as small as the article suggests, but it's still basically impossible (about 1 in 4.3 billion for a single character typo).

Perhaps the irony is that if you do happen to send bitcoin to an unintended address, you have a much greater chance of recovering it if that address belongs to a real person and is in use. If the address is not in use, then for all intents and purposes that bitcoin is lost forever.

There is functionally no chance of sending it to an address which is in use by accident.

The chance is about as high as the chance of generating the keys for a new wallet address and finding it has already been in use.