No, you can separate the front part of the reg to get at the spring stack without removing the bottle.
I see no problem with your bottle unscrewing off your reg so long as NO LOCKTITE IS USED, OR EVER HAS BEEN USED TO HOLD THE BOTTLE ON.
The regs are designed with blow holes so the worst that can happen if your reg starts unscrewing is the blow hole vents high pressure air and you crap yourself.
Loctite can plug up these blow holes turning your air bottle into a potential killer...