Yeah but take this situation
A says lynch blah blah and gives valid reason
B agrees and lynches
Then you are C (Sir Guy) and agree to lynch with them because thats your target.
Technically you didn't get the guy killed, A did.
The simple answer is: Sir Guy wins.
The complex answer involving how to avoid it:
This gets complicated. Let me call Sir Guy the lyncher, since that is what his role originates from in mafia terms anyways. There's a couple of strategies involving how you deal with the lyncher. The first is that you may not lynch until you have 3-4 suspects of who the lyncher might be. In this case Koriko, Apollo, and someone else whom I'm too lazy to look up were cases of the lyncher. You know that 1 out of 3 of those are the lyncher, you know that 1 is the witch doctor, and one might be either a random or a town role. This means you have a 2/3rds chance to provide forward progression for town.
My advice? Take it. The chances are minimal that the lyncher will have the other 2 as a target. Town people should never go for a definite lynch on day 1 (Preacher/Maid Marian), unless it's a Maid Marian Blitz to get rid of the KJD.
As for evil people, they still need to push a target day 1 if they have one. The point is to out certain roles for the murderer, remember that the murderer doesn't win if evil has a majority, murderer wins if he can kill the BttB, so witch doctor should push every day 1 regardless to out who the preacher is.
Another good thing is that Lyncher pushing on someone looks like MM pushing on KJD, or Preacher pushing on Witch Doctor. This could mean that evil eliminates him
That's how I think you guys should play against the Lyncher.