Claudius: unsure of who's a threat, but paranoid of everyone... especially Hamlet.

Claudius sees Hamlet as a threat, but he doesn't for sure think that Hamlet knows about the whole "ear poison thing." He just believes that it could be a possibility that Hamlet knows very little, to everything about the situation. King Claudius killed his own brother, he must be super paranoid, so of course he is going to believe that possibly everyone knows about him murdering his brother. so, yes, Claudius conciders Hamlet as a threat, but how nuch of a threat he's not sure.