I received a ticket response from DigitalOcean, below:
Thank you for reaching out, and I apologize for the lengthy response time. This does look like a blacklisting of our IP address space from Blizzard. Unfortunately, this isn’t something we would have any influence on, and while I can confirm that our network admins have reached out to Blizzard, I do not have any more specific details for you, I’m afraid. The range and duration of any limits at third party networks is fully at the discretion of the remote network. In this case, the best option would be to check directly with the Blizzard network to see if there is any particular information they can offer that would help move this forward. I apologize for any inconvenience, and I hope that this is helpful. Should you have any further questions or concerns at all then please don’t hesitate to let us know!
I fully expected that it’s outside their control, but I’m pleased that they have made representations to Blizzard. Would be nice if Blizzard would at least acknowledge this and keep us informed as to what they are doing to get things back to normal.