Does that really make any difference? The original calculation was just an average amount per person. It already accounts for the fact that multiple people are paying into the public coffers.

A exception to that is if the location has a meaningful number of businesses held by non-residents. But even then, the businesses are not operating as a charity, and the tax they pay locally is going to come from the local customers.

If you dig deep enough in specific cases, I'm sure you can find exceptions to all of this, where neither the owners or the customers are within the local population. But, the original claim was just an estimated average anyway, including people like children who are unlikely to be paying tax at all in the window of their childhood.