Non-applicable in said context.
This is of the same merit as when Sasuke awakened his 2-Tomoe Sharingan the night of the massacre, but we only saw him first use it, against Haku and Zabuza. It is quite evident that Madara already had his Sharingan, but he kept it a secret from his brother and his father. If you also take notice from the previous chapters that you are referencing, when Senju Hashirama is conversing with his father and brother, they tell him that Madara has killed many adult Senju's. Do you honestly believe he would be capable of that without his Sharingan? Obviously not.
Verdict; Not a plothole.