This nothing that Pyrrhus does is terribly interesting. There is, of course, the way the verse does nothing for the subsequent 7 beats of the line. Many a First Player will strike this painted tyrant pose and then hold it for 7 beats, which is often 7 seconds of beautiful silence, a breath in the torrent of words that this play is. It can be a small freeze, a pause, a suspension of time.
It could also be the end of the speech. Perhaps the First Player finishes here and Hamlet encourages him to go on. The contingent of Hamlet scholars that are obsessed with Hamlet’s inaction will often get excited about this Do Nothing – they will see it as a reflection of Hamlet’s doing nothing about his father’s murder. I see the connection but it does seem a little shaky – only because Pyrrhus is so clearly the villain here and his doing nothing is actually a momentary reprieve and is in this moment a good thing to do. So maybe we ought to see Pyrrhus as more a metaphor for Claudius who ought to have done nothing with his metaphorical sword hovering over Hamlet senior.
Or perhaps this nothing that happens is simply the most skillful sense of suspense in a suspenseful story.