The rinnegan is a evolved form , but nagato doesn't have the full package, He doesn't have the eyes of the true heir to it...
Madara's rinnegan you can obviously see he unlocked... Not only can he turn it off an on at will, but he is capable of using his ems jutsu etc with the rinnegan....
Rinnegan has its own unique set of abilities, and it won't help Nagato against tsukyomi... He's just as susceptible to Tsukyomi as any other....Kakashi's sharingan , though he was very skilled with it, didn't help him what so ever...because as Itachi said, You need sharingan and uchiha blood to resist tsukyomi and break it.
Note this is Itachi's tsukyomi, not sasuke's
Understand this...Rinnegan is not sharingan...
Sharingan offers certain abilities, Movement prediction , jutsu copying etc..
Rinnegan offers certain abilities...
It has actually never been stated that rinnegan offers any sort of genjutsu eye of insight ever...And even if it did it's still not enough to break tsukyomi SINCE he doesn't have uchiha blood..
Why is uchiha blood needed? Well the uchihas were born with high mental energy , which I believe is what enables them to be able to resist the mental torture..
Uzumaki's don't have that... they have a strong life force... And according to the databook, you can have body made of steel and you'll still fall to Tsukyomi, since it's mental damage