User blog comment:FairyRaven/Fairy Tail Chapter 391: Gray vs. Silver, Review and Commentary/@comment-24066070-20140704183210/@comment-85.221.190.231-20140706134439

I didn't meant that it might be important for Keith to let Juvia know, but for plot :P I was referring to Woest calling it pointless - we don't know if it's pointless yet.

From in-universe point of view, Keith's behavior seems rather stupid to me too. Explanations I see are a) he is not taking this seriously and he is sure that they're gonna kill FT mages anyway, so what's wrong with some gossip b) the way he reacted to Gray suggests that he is close to Silviora, maybe they have some plan or something, and they want to manipulate Juvia and others into something (no idea what).