Did Porsche not do something similar with the RS Spyder? Changing head of Aero before the races debut.
If Michael Pfadenhauer (He become head of aero on the RS) was still head of Aero before the hiring, he has now become the "General Manager Aerodynamics and Thermal management at Porsche AG" so that might indicate a slight reshuffling of positions, but nothing major like some are suggesting.
On the hiring time it seems he left Lotus at the end of December as indicated by a leaving present tweet, but has been tweeting about Porsche for some time. Take that as you will.