I tried to look after what their account on Hive was as I remember them posting here but seems google was giving me all other articles in existence about the collaboration between Barter and Hive except the Hive article. Maybe one of my readers can help
Well, through a quick peep seems like @bartertrade is the official Barter Trade account here on Hive and on Steem too since 2019-08-29. However, looks like they haven't posted or commented anything yet neither there nor here and at the moment they have 0.0SP and 0.0HP also.
As for the post of them that you remember, maybe this Tweet may refresh your memory somewhat. };)