Grammar god is meant to be an insult, remember.
Where would one be were one not at work? Not because one wants to be at work but because one (feels that one) must be at work. One feels that one is at work all the time anyway. You've joined me in this space. In a manner of speaking, certainly, you and I are here.
How much about language do you need to know in order to be a good teacher? Maybe know is the wrong word; maybe care is better. Like, do you need to be obsessed?
Not that I want to talk about language with others. Because they have their own ideas about language, of course, so often they want to be right. I just want to have fun. So rarely do people just want to have fun. Even when they're playing games.
Or then they refer to a proper grammar and so ask me what's absolutely right, but seldom are they happy with my arguments. "Well, but so what's the correct version?" Our Englishes may vary.
What I want from a teacher is the ability to think through a language and be jazzed by it, to find it fascinating and not a burden.