And Spinosaurus certainly never had perms - Zoan users have personal traits and appearance facets incorporated into all of their transformations
You'll find Sengoku's hair was beaded, like Daibutsu statues too. The way you're arguing makes me think you want Sengoku to transform into a literal statue. How useless is that? Lmfao its not going to be like-for-like exact. It's a manga. Lucci's facial hair and eyebrows appeared in his full leopard form. Dalton's weird triangle hair was evident in his bison form. Kaku retains his head shape as a full giraffe. Queen kept his facial hair as a Brachiosaurus. Jack kept his hair as a Mammoth. Page one kept his hair as a Spinosaurus. There's a theme here - can you tell?
Heck, Zoan users keep items of clothing when they transform too - which explains the glasses and coat. King was still wearing his BDSM gear when he transformed into a Pteranodon.
Face it. Sengoku was fully transformed.
First of all, transforming into a literal statue (which it isn't, it is a Hito Hito power, not a piece of inanimate stone) is as useful as transforming into a small wolf (Jabra), for example. Well, I must say, it is more useful because this mythical power brings abilities like enlightenment and shockwaves. and probably enhanced durability, and nothing supports that Sengoku's animal form wouldn't be able to perform that.
Spinosaurus never had perms and zoan users maintain certain traits when transformed —hence why I stressed that Sengoku's traits aren't simply retained but merged with his power, which is an hybridation manifestation we've seen before (I know this may sound weird, but Sandersonia and Marigold scaly boobs are the best example).
Sengoku's hair is big, rounded, beaded and golden in that form because his natural black afro is hybridized with the golden beaded hair of his animal form; he isn't a golden daibutsu with a black afro of natural hair, which is what happens in your examples.
Kaku didn't retain his head shape as a full giraffe, in fact the point of his hybrid form was the joke of how his squarish human traits were there. Lucci's full animal form doesn't have eyebrows, certainly not like those of his human self, and his beard is nowhere to be seen. Queen, Jack and Page One's hair is retained, not merged. The only example that may work on your part is Dalton's hair in bison form, but maybe just for the clear triangle in his forehead (which isn't even in Dalton's human self) because the tip on top of the head comes from how Oda draws some bisons (hence why Motobaro shares it too, so there's a possibility that Dalton's human hair is shaped after that of a bison and not the other way around).
Yet, you're missing the point: it isn't just one tiny detail that is retained, it is the amount of traits from human Sengoku (afro, glasses, facial shape and traits, moustache and coat) that are HYBRIDIZED (not retained like in most of your examples) and therefore turned into gold (like the scaly chest in the Boa sisters hybrid forms) instead of maintaining its human nature (so for your examples to work Jack's hair should be made of mammoth wool, Queen's moustache of scales, etc.). Sengoku's daibutsu isn't dressed with a Navy coat like King with his leather suit: the Navy coat is merged with the gold statue into a huge, golden Navy coat. Is King's suit made of pteranodon skin when transformed?
And all of this plus the fact that Sengoku's "full animal form" actually lacks the most distinctive trait from a daibutsu, which are the elongated ears (which is, at the same time, the most distinctive trait from Buddha himself).
So maybe you should be the one facing it or, at least, providing counterexamples that actually work and in an amount big enough to be comparable to Sengoku. You can pick one small detail in one zoan hybrid if you want to, but the issue here is that Sengoku's form has lots of his human traits combined with the statue (not simply retained) while it lacks others expected in a daibutsu.
By the way, why are you ignoring my second quote to your other post about zoan only turning specific parts of their body?