I re-read the ingame description of GDI on the Alliance server. It ends with "After the minimum membership, you may leave us at any time. However, once you do, you will not be readmitted for 72 hours."
Yet eestats shows a suicider's 2nd restart (#535) left GDI and switched to dictator at 2018-09-27 01:41:02
then gained NW (from stealing tech) then went back into GDI at 2018-09-27 01:56:01

so much for waiting 72 hours to rejoin GDI

another +1 for suiciders and their crappy rainbow-build hefty bonus restarts.