They've finally responded. They've doubled down on their original stance, but now also claiming the change is for performance reasons.

Which makes no real sense when you read the details of their response.

Their previous approach was to provide feed events based on people's watched repos. Now they're doing it from people's starred repos instead, which for most people is a couple orders of magnitude more data items. And also happens to be the data items with no value in providing events for. :/