The standard published MAP is more of an aid to deconfliction - not only form the other Heathrow runway's departure, but from the Helilanes and Northolt traffic.
At that time, Northolt would probably be closed, there will be little or no SVFR traffic so a further right turn and probably higher level keeps it moving to rejoin the sequence.
HD.... over to you!
HD - your inbox on here is full