John Gill Commentary 2 Samuel 13:27

"But Absalom pressed him, and he let Amnon and all the king`s sons go with him." — 2 Samuel 13:27 (ASV)

But Absalom pressed him
Which one would think would have increased his suspicion, if he had any, or have raised it in him; but his mind was blinded, that Amnon's incest might be punished and the threatening to David and his house be fulfilled on account of the affair of Uriah and Bathsheba:

that he let Amnon and all the king's sons go with him ;
if he had any suspicion at all, he might choose they should all go, that they might protect and defend him, if any attempt was made upon him; or, as others think, that no exceptions might be taken, as might be, if Amnon had gone alone.