Nah, Kaido at least had Big Mom directly state that about him, and he himself wanted to see just how strong the Supernovas were,and there is an entire panel of Hawkins explaining that Kaido does not kill or defeat his opponents quickly. He tries to break their spirits until they eventually agree to join his crew...
Imu, on the other hand, has not shown even a single real indication of having that personality trait, especially considering the circumstances he is currently in. But the fact remains that a clash by itself does not prove that your Haki is equal to your opponent’s. Loki’s Haki is not equal to Imu’s, just as Yamato’s Haki was neither equal to nor as strong as Kaido’s. The way Imu’s Haki was portrayed in Elbaf through Luffy and Gaban strongly suggests that it is superior to Loki’s, whose Haki was never praised or hyped by anyone. Neither Luffy nor Gaban ever reacted to Loki’s Haki the way they did to Imu’s.
Loki is basically the Yamato of this arc, with Haki on the same level. Luffy has superior Haki, just like Imu.
That’s why Luffy doesn’t need the insane physical strength of an Ancient Giant like Loki, plus a lightning-powered weapon and weak Yamato-level Haki, just to make Imu shed a few drops of blood. He doesn’t even need attacks as powerful as the explosive blasts Loki was unleashing with his thunder roars. All he needs is a single punch in base form, coated with Haki superior to Loki’s, to damage the tough guy Loki was whining about. LOL