Yeah, this isn’t what Hamlet said. Not at all.
They had a whole back and forth in which Hamlet clearly expressed that he would come ‘by and by’ and even repeated ‘by and by.” By and by is sort of the opposite of straight.
Is Polonius being deliberately misleading here?
Is he editing what Hamlet said to somehow soften the response? Or has he worked out some behavioral tick wherein Hamlet will do the opposite of what he says he’ll do – because Hamlet does, in fact, arrive shortly after this sentence.
In any case, the report is an inaccurate reflection of what Hamlet actually said. And we all know it.