Guildenstern! What are you up to here? With every thing Rosencrantz says, in this scene, Guildenstern seconds it with a shade of derision of Hamlet. Guildenstern escalates Rosencrantz’s assessment of Hamlet as distracted to a “crafty madness” taking something relatively benign and turning it into a something a bit darker.
Is he trying to curry favor with Claudius? Has he seen which way the wind is blowing and decided to side with the king instead of the Prince?
This portion of the scene might be played as a struggle between Rosencrantz and Guildenstern, as to what side they’re on. Rosencrantz could seemingly be taking Hamlet’s side, Guildenstern, the King’s. There’s a lot of interesting stuff going on with Guildenstern if you look closely enough.