Being clear on what the technical details of key escrow systems actually are is valuable, but may miss the crux of Snowden's arguments in this conversation with Lessig. Whether the Lavabit case should be construed as a law enforcement request for a mechanism that achieves many of the same goals as key escrow or should be construed as key disclosure points to the same sort of issue.
CALEA is one of many tools to be used and perhaps misused... mass surveillance conducted by eavesdroppers with a legal backing is just as morally wrong as mass surveillance conducted by eavesdroppers without one. Sometimes the scandal is what's legal, and sometimes the scandal is what can obtained without building key escrow systems directly into big tech companies' systems.