Nope sorry. Slack is a walled garden. And relying on a walled garden means handing over your control, freedom and privacy which eventually gonna lead to similar kind of exploitation/abuse.

As another HN commenter @SamWhited put it, "Using a proprietary protocol that doesn't allow any form of federation is an unacceptable way to build a global community". We need to develop and use FLOSS protocols/tools as much as possible.