The phrase "voicebombing" is inspired from Googlebombing and used incorrectly. Googlebombing is the art of getting a host of pages to link to a target site using an inappropriate phrase.
To produce a real "voicebomb" you would have to assume Google used a different filter for voice powered results and that a group of people set out to manipulate it.
This isn't really voicebombing because Wil Wheaton actually uses the slogan "Don't be a dick". He is a celeb with a strong association with the search term.
That said; I only found that out after this voice search and when Google responded by reading out Wheaton's name - I was so surprised it was funny.