Yes, it is.
He would have continued to level up and balanced his skills.
Oh, and I bet Suiton cast by Nidaime would have been much more powerful than his...
Oh, and I bet even if he COULD use Mokuton, he'd not have the same effect as when Shodaime...
you get the point.
it's not about KNOWING, it's about the power of the jutsu.
Currently, even a stupid-as-baked-beans-grand hokage with intelligence 10 can cast a genjutsu that pwns.
How ... er... fitting.
And also he can heal better than Sakura, but having no clue that sand does not belong in a wound ... Oo