Are you sure that the runner must derez on approach to avoid the Data Raven when encountered tag? I’m thinking about Page 3, Column 2, Paragraph(s) 1, FAQ
Conditional abilities resolve after meeting their trigger condition. However, if the game state advances past the trigger condition due to simultaneous effects or a chain reaction, then the triggered ability cannot be resolved.
Is derezzing not a change in game state? This makes me think you can use turn priority to Maxwell James in encounter, interrupting the Data Raven When Encountered ability. Then Corp cannot rerez since Runner is not approaching, irrespective of EMP Device.