What is foreboding about the squire's comment "I'll be as silent as the grave" ? Does it give us a hint of what is about to happen? What do you think that will be?

The Doctor wants to keep this map as secret as possible for, "We are not the only men who know of this paper." Squire says that he will be "as silent as the grave." His choice of words give us the sense that people will easily kill over this information and that indeed, men will die over it.