Aramaki never mentioned Kaido’s strength once, he brought Kaido’s regime as what kept the others away. What would he have gained from going in Wano when Kaido was having a business with the WG and was an useful idiot keeping rookies away from the One Piece? Kaido kept him away because when he was here he had literally zero reason to go in Wano.
Why would he be afraid of his strength when he was breaking the bones of someone with durability equal to Kaido casually and came to face an alliance that defeated Kaido AND someone equal to Kaido? Except if he’s supposed to be written as a complete schizo this makes zero sense.