No, it's not. It completely ignores the information the manga provided us.
This scene explains to us how enma works.
Nowhere in that scene are we told enma retains the previous user haki. That information is coming from a blacksmith who creates dangerous swords. An expert. Someone who knows what they're talking about.
Zoro's performance on the rooftop is very easy to understand when you understand the benefits to using barrier haki offensively and defensively.
Hyou explained to us that barrier haki can be used defensively or to increase the offensive power of an attack.
You alse must have to understand the strength and amount of Zoro's CoA haki and his level of control of haki at the time. Remember, Zoro using enma would help him increase his haki control.
The above scenes shows 4 important info about Zoro:
1 - How Zoro could easily cut a cliff using only the physical strength needed to cut a tree because of the strength and amount of barrier haki released from his body. If Zoro put more physical strength into his attack the stronger it would be.
2 - The incredible large amount of CoA haki Zoro has. He didn't know the sword would force out his haki before he used it so he wasn't ready to stop it. Yet, only his right arm shriveled up. We were told weaker swordsman entire bodies would have shriveled up.
3 - Zoro was easily able to take all of the haki left on the sword back into his body. That's the first time we have seen that. It's showed he has always been able to control large amounts of haki post TS.
4 - Nobody except for Oden has been able to control enma. Even the Scabbards couldn't control it.
As you can see Oda hyped up Zoro's CoA haki and portrayed it at a high level.
From all of the info and facts provided you can see Zoro's performance on the rooftop was believable.
Cutting the horn was because Zoro used barrier haki offensively.
Blocking Hakai was because Zoro used barrier haki defensively.
Actually, he did hype up Zoro's haki.
The first time Zoro used blackened haki he shocked and amazed Oden's retainers and beat a character's who haki was hyped up to be invincible.
Zoro scarring Kaido, a character with an invincible body who has only been scarred one other time, was one of the greatest feats in the manga.
I already explained how Oda hyped up Zoro's haki more in my post.
Enma never outshined Zoro. That's BS you and the rest of Zoro's haters claim. Even when Kaido stated he felt a strange haki. Strange is defined as: not previously visited, seen, or encountered; unfamiliar or alien. You and others either ignored it or tried to claim Kaido was feeling Zoro and Oden combined. Instead of the most obvious and logical answer, he felt Zoro's haki. Since he has never fought Zoro before his haki would be strange or unfamiliar to him.