"How unfortunate! If we only could have done things to save time...but well, I guess it's too late now", he commented on Robert's sudden departure in tone which was imbued by sarcasm.
Sean reacted to Robert's gesture by doing so as well, extending his arm and grabbing his counterpart's hand, although for a moment he thought about slapping Robert instead, as witty counter-effect to Robert's typical, but vexatious "games" he tended to play. To his consternation however he was able to see Gregar from the corner of his eye, who was - as always - hanging around the entrance of the dome. Unfortunately Gregar has been staring in their direction the entire time, ever since Sean approached Robert, and he was not even remotely as humorous as Robert.
So instead of risking to get thrown out of the airlock, Sean continued with his already begun action. He exchanged with Robert a firm handshake and both returned to devoting themselves to their particular profession.