I know Horatio has to read this out loud for the benefit of the audience. We need to hear it to understand what happened to Hamlet. But the sailors don’t need to hear it. So it’s funny that he reads this aloud to them, especially since he probably suspects that it is from Hamlet and a level of secrecy is likely required. But he reads this to sailors who aren’t even sure of his name. It is an odd choice if you take the theatre factor out.