It could be true. Catalytic converters do a pretty good job of filtering out most pollutants. They also increase CO2 emissions in a variety of direct and indirect ways. Everything else is lower, though.
The way to make EV tires pollute less is to not chase 600+ mile range. Keep them around 300-400 miles, and use further battery improvements to reduce weight. There's no reason EVs have to be heavier forever. With better charging infrastructure, 400 miles is more than enough.
The way to fix everything else wrong with them is to not make cars the default mode of transportation.