Why was Lucius Fox fired?

I thought it was strange particularly given how he does it in that scene.

"Could you please gather up all the damning documentation that implicates Wayne enterprises in losing a weapon of mass destruction? Oh by the way, I'm firing you before you complete my instructions and are totally able to just take those files and walk out the front door with them?"

Entrusting a clearly disgruntled employee with those files is ridiculous. Unless...

Willaim Earle worked for Ras Al Ghul.

Earle may be clueless to the significance of this action. But Ra's Al Ghul knows things Earle doesn't. Consider the aftermath of Ra's Al Ghul's terrorist attack on Gotham; The ensuing investigation. A piece of stolen experimental Waynetech killed an American city. If they look at Wayne Enterprises books they are going to find that there was in fact someone that was stealing military hardware from Wayne Enterprises and using them for acts of violence in Gotham.

Ras was framing Bruce Wayne for killing Gotham. His coup de gras to the Wayne family legacy. Earle may not have known what was happening, but Ras bragged about infiltrating every level of Gotham. Earle got off light at the end of the movie.