To be fair, this Slack chat isn't reddit's internal company chat. This is a group with default sub-reddit moderators (random volunteers not associated with reddit the company) and a few reddit admins.
But yes, it's pretty awful and highly unprofessional. spez's comments in the chat are unprofessional and concerning as well.
And I thought that I work in an unprofessional company on a useless project. I feel a lot better now.
This reads like a chatlog from minecraft server for teenagers.