Servo doesn't move if I detach it AFER the write?
The detach() function probably stops the data pin from outputting the servo control signal.
Your code disables the control signal a few microseconds after it is enabled.
The cotrol signal is never generated.
Furthermore, a servo requires the signal to be present at all times for it to keep its position.
When your programming includes real-world events, you have to think about the time frame of the events, and about the time frame of the running program.
Think in the terms that the program can loop 100,000 times before the servo has finished moving.