Yeah, it's either way. I don't have anything to really back up the G1 guess, it's just a gut feeling. The problem is that if you're only in it for the steelbook, you're possibly paying over $20 over the PC edition for the chance that it's going to be G2 (unless you wait and see of course...but then it might be too late).
Pre-order bonus steelbooks, for which empty, unsealed steelbooks are given in addition to the standard case, tend to be (but not always) standard G1 across all platforms (out of laziness, I suppose), while special editions follow the corresponding disc format and actually house the games themselves.
Then again, this is called specifically the "Steelbook Edition", so it's a little vague. It's not as rigorous as a true Collector's Edition, but it's not just a pre-order bonus either. Brink is an example of a "Steelbook Edition" that was G1, but it's not conclusive obviously.