New Theory! The Father of Zaheer.
Okay; This is probably a crackship mad idea, but I kept looking at Zaheer while watching Korra and he reminded me of someone from the A:TLA universe, but I couldn't ever quite put my finger on it.
And then it hit me:
Could Zaheer be Teo's son?
That might explain how he developed such a strong interest in preserving/studying air nomad culture. After all, to the average non-bender, it's been seen to be a very boring subject unless you're fully willing to immerse yourself in, and for a non-bending child to learn about the culture in a rapidly decaying temple overrun by machines and technology; the sight could've possibly led young Zaheer to become inspired and want to preserve and teach what he knows of the Air Nomad culture.
Not to mention That …