I have no problem with this player's character removing the limb. In fact, it's a good idea considering what she is planning. She wants to have all of her tech in the arm, datalock, commlink, and smuggling compartment. Then, she wants to put a microbomb in there. If she gets nabbed, the arm comes off, and gets tossed as far away as possible. Thus, no evidence, and nothing to trace back to a Johnson or Fixer. She WILL get busted for possessing an explosive device without a license... But, yeah. Just need some way to get that arm off. Monoblade IS an option, really... I like the idea, and want to support it with something rules like.
Of course, I AM the GM in this situation. So I can just say all cyberware comes with a quick-release mechanism for changing out limbs, but only people trained in cybertech know about it. Because it isn't as handy as modular systems, and damages the connective wiring in such a way that requires a bit of work to fix when you go in to replace said arm.
I love the easy breakdown option, and may be something to do later. And yes, I know blowing up sensitive cargo is against the courier's rulz, but not letting someone else trace cargo back to a Johnson or Fixer is more important than anyone's silly rulz. Because, as Han Solo said, everyone gets boarded once in a while. She would be the go-to person if sensitive stuff will be useless or damning if someone else gets a hold of it. Now, if she makes a habit of not finishing jobs, her rep is going to be going down the drain faster than a goldfish in a toilet...