HER is big and messy and rambling and often lovely (enough that I'll go 70 overall) but I'm pretty sure I'm calling bullshit on the ending.
Spike Jonze in Q&A: "Did everyone understand that the safety pin was to keep his phone from falling all the way into his pocket? "
Rando in audience: "I thought it was to keep people from stealing it...cause people steal phones."
Jonze: (pause) "Yeah. Maybe it's that."