The best solution to the OP could be either to take a screenshot of the mobile boarding pass and send it to your employer that way, or when doing OLCI you can save your boarding pass as a PDF before sending it to the printer. In other cases there is no way to obtain a boarding pass after the fact. You could always save your boarding pass and scan it later I suppose.

But I agree, an overall asinine policy from your employer. Generating your receipt after the flight will indicate whether a segment was flown or not.