When I landed in Dubai and thought I was unable to access the F lounge in Dubai unless I was 3 hours prior to departure, I cleared immigration, took the train ride, and then went back to the terminal till I was confident I was 3 hours to departure to gain access to the F lounge, so no issues at all exiting and re-entering the terminal.
FT101 is still on my ignore list till he offers me a one way
F-class ticket with EK from Dubai - Kuwait to compensate me for wasting 3 hours taking the train ride to the city rather than enjoying it in the F lounge.
Speaking about the subject, I still can't understand why people want to leave the terminal when they are flying F/J class rather than spending it at the Dubai lounges since I don't mind spending another 12 hours in the F lounge in Dubai.....