Hunt was not the Commander of the Army of the Potomac. That Sickles was made to believe Meade was ignoring him doesn't exhonorate him from disobeying Meade's order. That sounds like an excuse not a reason.
But Hunt
was sent by Meade to check if Sickles was correct, and Hunt agreed with Sickles.
The question that needs to be asked here is this - in what way can Sickles get the information to Meade that there is a problem, and how should Meade have then reacted?
What Sickles did historically was to repeatedly inform Meade that there was a problem in his opinion. He said the position was weak, and he said that the enemy was planning to attack in his sector (the second point is true).
Meade's response to this could have been:
1) Take Sickles' comments seriously and view them as correct, and reposition Sickles in a better position.
2) Take Sickles' comments seriously and go over to check the ground, to affirm that Sickles' current position is the correct one.
3) Send a staff officer (like, say, Hunt) over to check if Sickles is correct, and if he is then take Sickles' comments seriously (as above).
Instead, what Meade did was to dismiss Sickles' concerns. He responded to Sickles saying the enemy was going to attack in his sector by saying that
all commanders think the attack is going to come in their sector (which led to him ignoring a true warning of the attack position) and he did not go over to check the ground - something he could have done at any time and which would have consumed some time, certainly. Instead, he sent over Hunt but then didn't listen when Hunt concurred with Sickles, which means he didn't send over Hunt to actually find out if Sickles was right - he sent Hunt over to shut Sickles up.