[rit]

Why would it confirm it? "Correlation does not imply causation".

He may be pulled in by the same rumours as everyone else and being overly cautious. Just because he does this doesn't indicate he has confirmed or denied the existence of a slave microphone bug.

Just that he believes strongly enough in the possibility to be cautious.

[Jach]

Correlation may not boolean-logically imply causation, but it's evidence of causation. http://oyhus.no/CorrelationAndCausation.html

The actual cases I've seen (some linked on this page) are of specifically targeted individuals having their phone receive a command to turn into a bugged phone. I don't think all phones are bugged by default. This fits with Snowden wanting people around him to sound-proof their phones as they might be targeted.