is that not the "advance" setting?
That's spacing (through sidebearings), not kerning. Kerning in this case is contextual advance.
Now, it would be cool to have, but when it comes to pixel fonts, natural irregularity and "planning around X" are the common state of things. Kerning will be a waste of time 99% of the time.
I can see it implemented in a painless way as an on/off feature for punctuation like the comma and so on, but it's still a very extra thing to have here. After all, every pixel font any of us has ever liked was never kerned! The dev can think about this later IMHO.