Is there a problem with carrying a crew member in the flight deck? Is there a problem with carrying a colleague in the flight deck? Please, let's not be silly as the politicians act.
Unluckily for everyone on that flight the extracrew member in the flight deck was a flight attendant instead of a pilot, as it many times happens.
Extra crew members have been proven, in courts of laws, to have aided in accidents and incidents more than the crew of the A/C (this is probably due to not having any duties on board; hence, being able to help).