wvmarle:
No.
I2C is likely too slow for the required timing accuracy to begin with. Just a simple pin read can take as long as 1-2 milliseconds - where you need to be in the microsecond kind of speeds for that sensor.
I searched this mater that you said, for mcp23017 and pcf8574, and nowhere tells that dht not worked with port extenders,
In this article Learn How to Use the DHT22 with an Arduino; Full code examples included tell that we can use dht22 with mcp23017 !