[grzm]

As typically used, the term "shadow banned" is a ban without alerting the user that they are banned. That's not the case here. On HN, "banning" means to to have your posts be dead by default. And "banned" is the language 'dang himself used in the message to the user.

[0des]

There are also numerous bans with no notice at all, just a sudden stream of gray comments that are 0 minutes old.

[grzm]

Yes, there is also autobanning and filtering software. But that is not what happened here.