Approval

I think that when Horatio says, "So Guildenstern and Rosencrantz go to 't", he approves of their deaths and what is to come. After all they were taking Hamlet to his death. Whether or not they knew what was going on they never really seemed to care and went along with everything Claudious said and yet they are suppose to be really good friends of Hamlet. Besides Rosencrantz and guildenstern are such minor characters that I doubt Horatio really cares what happens to them. Horatio knows that they were Hamlet's friends from school, but ever since they arrived in Denmark they have done nothing to show that this is the case, instead they spend their time doing Claudious' dirty work. From everything that Horatio knows they have done nothing to show that they really care about Hamlet, but instead they act as if Claudious' opinion is all that matters.