Madara is still an Uchiha... and the Sharingan is a BloodLine Limit; a Kekkei Genkai. So I assume it means that if you have the blood of an Uchiha running through your veins, and have already achieved the MS/EMS, you can use those techniques.
Maybe it also has something to do with Hashirama's Senjutsu chakra... but, so does that mean Susanoo isn't only an eye technique?!
... or, it could just be another asspull to save Madara with plot.
The optimist in me says the former is true. The realist argues the latter.