Actual title: Tesla had to respect standards set by the european commission and is doing this because they are legally ordered to.
"The right to build a charger comes with responsibility to service electricity to any EV car."
The EU, and in particularly Germany, is strongly nudging Tesla that, if they do it now, then right now at least they can do it in their own terms, and existing experience can flow into legislation.
If they wait, then they will need to complain with whatever is legislated, and without any experience, they won't have a seat at the table (while other EV charger systems with experience will).
I see it more like: Tesla has good charging infrastructure and Tesla can scale chargers faster than cars (with cars production they are battery constrained).
If even Shell and BP are installing electric chargers at their gas stations to get a small cut of this market it's a no-brainer for Tesla
Who really knows the strategy behind their moves, but legislation forcing their hand certainly feels plausible. Which company wouldn't want to own a proprietary network of chargers all over the world and extract as much money as possible?