It still doesn't make sense unless that info is going via mozilla's servers. Software running on your PC doesn't need permission to process and send data that you are giving it, to send it to the places you intend.
Mozilla legal apparently think otherwise. They have been spooked by the recent California legal movements which can apply the label "sell" to behaviours we wouldn't normally consider selling user data, like setting the default search engine.
Where has Mozilla legal clarified that in its entirety? They could limit the data to that very need inside the ToS if that is how they felt and wanted to be transparent.