Just tape the levers. Chances are you're going to knock the bloody things and the spring will unattach or Apollo will just pull on them and then you'll just have to faff around with them again.
Rogan, that bike is so doing it right.
I did the biro spring fix (successfully) on S500s. I use a normal crimped cable end cap though, so it would definitely have popped off if you'd been stupid / absent-minded enough to pull the lever with a bit of force.
I really disliked the levers though. Hollow, flexy, hoods too flat for my liking, and a socking great hole where the shift levers should be.
TM ruined my biro spring