It appears the extension would like to read and change the data on any website I visit. I assume users are the product here, so this appears somewhat sketchy since I'm not sure what personal data of mine is being sold.
The reason that permissions are needed is that the extension monitors how long you read on each website. But that data never leaves your computer — it's just used to compute the stats we show you in your dashboard.
Read Across The Aisle is related to my main startup, BeeLine Reader, and it was just something we did for fun, and to help with polarization of news consumption.