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They can only get a change of venue if the FB page substantially affects the jury.
Think about this: very high profile cases get tried in the place where they occurred, even when the media coverage is extensive.
I don't think that you will find that one FB page makes it impossible to identify 12 people in a community that haven't heard of it. Even if they have heard of the page (which, odds are, they haven't) so long as they can base their decision on what happens in court and not on anything they heard outside of court, they are eligible jurors.
Also, the attorney for the state and the attorney for the defense will have a chance to talk to the jury before they are selected. As such, the attorney for the defense can ask potential jurors if they are aware of this FB page, etc. If they are, the attorney can strike them from the jury.
In short, the existence of a FB page will not impact the trial.
The few times I've seen judges grant a change of venue, it has almost always been after they tried, but could not find an impartial jury in the county where the crime occurred.