It's possible I've been living under a rock, but while I'm aware of rat being pejorative, I'm finding out in this thread for the first time about the anti-semitic undertones.

It's pretty clear that the difference is context, but I also don't think there can be clear guidelines if Twitter is expected to delve into the context for each tweet its users make.

In fairness, context typically doesn't provide smoking guns as pungent as this one. I'd still say it's not beyond reasonable doubt (and I'd guess most would be ok with that for a Twitter ban -- it's not prison or death).

So, sure, everyone should call it a dog whistle on the preponderance of evidence, but there were almost certainly better grounds for the ban. I doubt there will ever be a good ban target whose only giveaway is dog whistles.