ETA: Several people have since come forward and stated that they voted for both
Babel and The Mountain in the Sea or A Half-Built Garden or all three, so this
should be visible in the EPH data.
That seems like the smoking gun the results were rigged.
For those who aren't familiar with these awards, it's important to note that the awards and the organization that run them have basically no governance structure other than people showing up at the yearly convention and voting.
Each year's convention and the corresponding awards are run by whatever committee of people submitted the winning bid for hosting the convention that was voted on by anyone who attended the convention two years previously.
The rules for running the convention and the awards are set by a meeting at each year's convention. Anyone attending the convention can vote at the meeting.
The only standing committee is the Mark Protection Committee which only has the power to enforce trademarks. Everything else is handled by the hosts of that year's convention.
The upshot of this is that the only action that could potentially be taken about this is for someone to submit a proposal to be voted on at the next convention in August in Glasgow.
I think WSFS is going to have to change its structure to deal with the fallout from this.
The Hugo awards should be managed by the WSFS, not the convention committee. That made sense in the past with slow communication and trustworthy committees. But now the voting can be handled online from anywhere in the world.