... I believe it means that the Sheriff would be willing to say whatever needs to be said to get someone to participate in his game.

[That said--]

Whether or not he is telling the truth... is a different matter entirely, and one you should think of very carefully if you are ever put in that situation, Young Noctis.

It is a decision that cannot be taken back.

[Lives are at stake. But they're at stake in Noctis' home, too, if that happens, possibly. So Barnham...can't give him a definitive answer. That's something Noctis has to figure out for himself.]