Got it, so just chop the throttles, and it manages best rates from there?
Not sure what you mean by 'best rates'.
I've never flown an Airbus but the RTO function should be similar to the Boeings I've flown.
On the Boeings, you set the autobrakes to RTO prior to the takeoff. At about 80 knots on takeoff the RTO mode is armed. If the thrust levers are brought back to idle after that point the autobrakes apply max anti-skid braking and will bring the airplane to a full stop if no other action is taken.
The RTO procedure is for the Captain to bring the thrust levers to idle, verify that autobrakes are operating and, if not, apply max manual braking, extend the speed brakes, then apply max reverse thrust. The F/O makes note of the max ground-speed achieved, verifies the RTO braking, speed brake extension, and thrust reverser activation, then notifies the tower of the rejected takeoff.
The only thing that is automatic is the application of max anti-skid braking.
Once stopped the OAT, weight, and max ground speed is used to determine the brake energy which defines the risk of tire failure/brake fire. If the brake energy was low, and the problem that caused the reject is corrected, another takeoff can be accomplished without returning to the gate. If the brake energy is high(er) then you wait a specified amount of time (the heat peaks 5-15 minutes after the reject) then inspect the tires to ensure that the fuse plugs have not melted. The inspection is not time consuming but you must wait the specified amount of time to allow the fuse plugs to melt if they are going to melt.
As far as the reports of an "auto abort"... Airbus has developed some warning systems which look ahead at the runway available and these systems are on the A350. I have no idea of the specifics of what these systems monitor, when they monitor it, and what they do when their tolerances are exceeded. I would expect just an audible warning but I don't have any information on what it does. Perhaps a false alarm from such a system resulting in a pilot-initiated rejected takeoff? I don't know.