The recognition of Chu Di by Taichu had no reason, it was simply an idea that emerged when the two Respected God-Hidden witnessed the Sky Desolate Halberd.
You must be aware, with their status, they would not have unfounded ideas.
Otherwise, why didn't Immortal Emperor Jiang Li of the 390th world, and the idle Jiang Li of the 809th, possess the Sky Desolate Halberd?
The implications of Taichu's recognition remain unknown.
Taichu was born before the Heavenly Dao, s/he was deceased, but the whereabouts of the corpse remains unknown.
Taichu's body was not under the control of the Heavenly Dao. It has tried to find it, but it simply could not.
In the dark, Taichu's body had an undefinable, indescribable mysterious power preventing it from being found.
Theoretically, the remains of Taichu couldn't be refined, let alone forged into the shape of a halberd.
All of this substantiates the claim that Taichu's remains recognized Chu Di.