Per said, a month ago, "is there anything you can do about it in that case, otherwise we will have to institute very tight limits of invites per day being sent from federated domains", speaking about specific domains, and speculating about a possible future strategy.
FSF says (paraphrasing): "we have this symptom, we're convinced it's for this technical cause... " (so far so good) " ... "and this email thread says that Google is doing it on purpose". Bullshit, that thread says nothing of the kind. Stick to what you know.