"Line level" is nominally 1v, and a "medium" impedance (ie it won't drive
an 8ohm speaker, but it's not 10,000ohms).
I can't see why that pin would be anything else. What's it supposed to
drive? An audio amplifier, or even specifically some audio input on a
device, which would be "line level".
Precisely because it's brought out, I'd assume it is line level. I have
no experience with a IIC though.
Of course, the caveat is that "nominally 1v" or "line level output" has no
real standard in terms of level. I have an amplifier that's fed from a
VCR, a DVD player and a CD player, and I generally have to adjust the
volume when switching to any of them, because the "line level output" is
not the same from each.
Michael