They could still use the astronaut/scientist aspect. That's long been a part of the character's DNA anyway, it just hasn't gotten as much play as the hotshot pilot. In some versions of his origin, the flightless trainer Hal was in when Abin Sur's ring chose him was actually designed by Hal himself. When the character was first created in 1959, a test pilot was the coolest of the cool. If he was created only a couple of years later, he would've been an astronaut, so making him an astronaut now does make sense, and part of being an astronaut today is very much about being a scientist.
Hal Jordan is made from the same mold as James T. Kirk, who, while often characterized as a cocky womanizer as well, is more than those two traits. Kirk was a diplomat, an explorer and philosopher with a genius IQ. Same goes for Hal. It's like someone saying that Batman can never be portrayed as anything but a grim, humorless *****e, when Adam West proved that he can.