No rules, it's their stake and they get to use it however they like.
There have been a few flag/downvote wars over the years - usually between two whales or two groups of whales, with mostly little fish actually getting the downvotes.
This time, it's just a bunch of whales on one-side, downvoting a bunch of journalists and other content creators, clearly because their content is so unacceptable to those whales' political ideologies.
Say our efforts of year on HIVE might go away in a min.