Reasons I think this could potentially be the case are:
1. Oden's Superhuman Strength
Oden is said to have had superhuman strength since was a kid and the most logical explanation, that can be used to justify that I think, is his bloodline. However given Momo, doesn't really seem special in that department and the way Sukiyaki's retainer was stating Oden's deeds in awe of sorts, you'd have to wonder if the Kouzuki clan really birth superhuman fighters. Putting that aside for the time being, if we assume that Zoro's roots lie with the Shimotsuki clan, given Zoro is also superhuman of sorts, then we can make a connection between the two being that both’s roots lie with the shimotsuki.
2. Oden's strength as a swordsman & the strength of the shimotsuki clan in general
I think it's been implied as much that Oden was the strongest swordsman on Wano when he was alive, but then if y'all remember correctly, the Shimotsuki warriors are referred to be the strongest in the land (this statement was made by Oden himself) and rightly so, if you think of the kinda warriors they produced over the generations like Ryuma, Hyou etc. So given Oden isn't a Shimotsuki in name, it's a bit of an anomaly, which can indeed happen, but if you think of Oden having inherited some of the Shimotsuki blood, then it fits with the narative.
3. Oden's swords (Enma in particular)
Enma was made by Shimotsuki Kozaburo, so basically the Shimotsuki clan. In other words, it's a treasure of sorts of the Shimotsuki clan especially considering it was made by Kozaburo who escaped Wano, so ideally, you'd expect a Shimotsuki warrior to wield it, so how did it make its way into Oden's hands? I know it's stated Oden was the only person on Wano able to wield that sword, but how did it make it's way into Oden's hands in the first place, and why did the Shimotsuki easily part with such a sword. Also did Kozaburo just randomly make that sword or was it particulrly made for someone? The Shimotsuki warrirors are said to have swords made for them at birth, and Oden was already in possession of Enma 41 years ago when he was 18 years old, so maybe it was given to Oden at birth? If y'all think about it, we are still yet to see even one Nitoryuu swordsman on Wano iirc, meaning it's pretty rare, so Oden having inherited the Ame no Habakiri from the Kozuki clan and Enma, from the Shimotsuki could potentially have birthed a Nitoryuu swordsman ^^
4. Familiarity with Hyou
Oden and Hyou seem to have a very familiar relationship. Heck Hyou smacks him around when he fcks up, which regular folk wouldn't dare to do given he's the Shogun son so you'd have to wonder if both don't have familial ties. There's however a possibility that Hyou can smack Oden around just that coz of how respected he is, and that the two bonded over the events of the Harem revolt event.
What do y'all think? I know there's a lot of speculation, but I think it's interesting nonetheless. Also if y'all have any ideas, please share..
