https://peering.google.com/#/infrastructure send to say otherwise. It's in the best interest of both parties, so not sure why they wouldn't have done this.
From a network administrator's point of view, they're an absolute joy to work with too.
If you're share any IXes with them at all, they'll peer with you. Private / appliance based peering has additional requirements, but that's par for course.
Most of the pushback is on the ISP end.