"Don't like" is different from "Absolutely hate" 

The new contact over at that colony they couldn't track, they have no way of contacting them again. They were also peaceful and posed no threat, its like opening your door to find a mewing kitten, the Draconians are like hearing your window being smashed in and seeing a machine gun armed thief. Plus the slight disturbance was in the GC, where there is almost literally nothing to disturb regular signals. That area is also associated with the Dracs, they want to make sure there wasn't one who survived and are trying to estiblish a presence in the MWG once again, and that wouldn't go on the offensive, they go on the defensive.