Times change and companies need to adapt with the times. 2015-2022, exclusivity would be a huge positive for Tesla. Their vehicles would have lots of charging stations while other vehicles wouldn't. That's great for Tesla.
When the National Electric Vehicle Infrastructure plan, it became clear that CCS would become the dominant charging standard in the US - unless Tesla acted fast. Tesla's port would go from an advantage to a disadvantage. Tesla has 12,000 US chargers today. Maybe the company would make that 25,000 by 2030. The NEVI pushes for 500,000 chargers by 2030 with the CCS port. Toward the end of the 2020s, Tesla would feel pressure to switch to CCS because the majority of chargers in the US would be CCS. Tesla owners would complain that their Tesla vehicles used a different port from 95% of the public chargers.
By pushing the industry to adopt the Tesla charger, they ensure that chargers built using the NEVI money will most likely have Tesla ports. They could even argue that the administration should drop the CCS requirement given that the industry has moved to the Tesla port.
Tesla's port would have gone from an advantage to a hinderance. If Tesla didn't move the industry to the Tesla port, they'd eventually have to move to CCS. People would want their cars to be compatible with 95% of the chargers out there. When Tesla announced a switch to CCS, sales of current vehicles would likely crater. With Tesla abandoning their port, people would want to wait for the new model. Tesla might need to offer steep discounts to get people to take the "old" port. Instead, by moving the industry to their port, they put the uncertainty on competing vehicles; they make potential punchers of competing vehicles more likely to buy a Tesla or delay their competing purchase. That either adds to Tesla sales or makes competing companies question their EV commitment.
It's not that Tesla wanted to give up their moat. It's not that Tesla wants a bit of charging revenue. It's that if 95% of the chargers in the US become CCS, that moat is trapping Tesla in rather than keeping competitors out. Yes, having Supercharger exclusivity would still be an advantage for a few more years - and it will still be given that it'll be a couple years before competitors have Tesla's port on their vehicles. However, Tesla doesn't want the situation where their port becomes the odd one out where Tesla owners need to fumble with CCS adaptors. Maybe Tesla gives up a year or two of Supercharger advantage, but they ensure that it doesn't become a disadvantage.