I don't see it that way at all. Those egregious egress charges still apply while you are actively using GCP, encouraging you to put everything in GCP, and eschew multicloud.
This seems to me more of a "try us out for free" play. Bring your big data here, if you end up not liking it, we won't penalize you for taking your data out. Given that GCP is running at a very distant 3rd, they need to make plays like this.