Unfortunately fuel being burned in other countries is still heating up their environment.
Also idk if you've heard, but India isn't exactly a rich place. A lot of people can't afford EVs. Despite the fact that yes, the Indian market has cheap options available. But my man in the tweet has been nursing a Hyundai i10 for 15 years. He ain't exactly trying to spend money on cars.
The entire policy is designed to hurt poor people that are car dependent (if you look at the photo of the street in his other tweet, you'll see why he isn't walking the 1 kilometer. There's no sidewalk).
If the government also gave him a good public transit option with AC, the fuel ban could easily be justified. As it is now, rich people will buy newer cars and poor people will be criminals, or take on debt they can't afford to get buy newer cars.
He also posted a photo of the road. It's 2 lanes of chaotic traffic in each direction, no sidewalk. You can't walk there, you'll get hit by something sooner or later. It supposedly also gets up to 44C (of course on an asphalt road the air temp might be higher than that). I choose to believe that because apparently the temperature record in New Delhi is over 50C.