Nope, two separate cases.
For the Whitebeard one, their Haki didn't nullify Whitebeard's Quake or render it nonexistent, their Haki formed a shield. The Quake hit the shield, used up its power, and faded because it couldn't penetrate their shield. A shield like that wouldn't work on Kuma, because whatever he touches goes flying regardless of the force behind it. Cases in point, Zoro's slice and Luffy's punch. If someone did that and created a shield of Haki around themselves, Kuma would just send the shield flying as well.
As for Marco, that ties in with Haki's ability to touch the DF user's body. Before I get into that, let me explain how Marco's powers work. Marco's powers work by transforming his human body into a Phoenix body, effectively "hiding" his human body under the Phoenix's form. Marco's Phoenix body is capable of regenerating damage, but his human body cannot. This is proven by the fact that when his human body was struck by Kizaru's light beams while wearing Kairoseki, they didn't heal. It's important to note that Kairoseki has the same exact effect as the sea, meaning Marco simply can't control his powers, they don't go away. This proves that Marco's human body cannot heal on its own, only his Phoenix body can.
Busoshoku Haki allows the user to touch the body hidden away under that protection. When Garp punched Marco's Phoenix body, the fact that it was laced with Haki means all the damage was done to his human body "hidden" away under the Phoenix's body. It didn't nullify his Devil Fruit powers, it didn't erase them, it simply allowed Garp to hit Marco's body, which can't heal when it itself is damaged. Haki doesn't negate or nullify Devil Fruit powers, it just allows you to touch the body underneath of transformations, such as Luffy's Rubber transformation, or Marco's Phoenix transformation, or a Logia's elemental transformation. A Haki-laced fist would still be repelled.
Garp did not render Marco back to his human form instantly, Marco transformed back to his human form after the impact, proven by the fact that when the smoke cleared, his wings were still transformed.
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If Busoshoku Haki works like how you said it does, and negates a Devil Fruit power, how did Aokiji reform after being smashed to pieces by Jozu's Haki-laced tackle? If it negated his powers and deactivated them as your claims mean they would, he would have broken into pieces of flesh and died instantly.
