

While I think Imu isn't the final villain which I explained in a thread with 7 reasons, this might not be the same Wifi-Haki moment between Shanks and Greenbull.
If Joy Boy was at a level that he can simply hurt Imu with Wifi-Haki, then Imu is simply too weak to compete with EoS Teach level opponents.
This might be something else,
We know 5 Elders all having abilities similar to DF Mythical Zoans not 1 of them has Logia or Paramecia, and also all has regeneration ability, and summoning ability are all shown to be different, and they all kneel before Imu, and they also all have telepathic connection with each other, so that my assumption is, somehow Imu's and 5 Elders powers are tied together, and they are all connected with each other in a different way. It could be that if Imu is the power source of 5 Elders, and they draw power from Imu as well as their immortality so they are loyal to Imu. Which means its a different dynamic than a regular boss and underling relationship.
Thats why when 5 Elders ability were suppressed by superior Haki, Imu probably felt the Haki directly through them. If Imu got hurt by wifi-Haki, I don't know how Oda will balance the power levels from now on.