This seems a lot like you making assumptions about their expectations and/or acting on their expectations/your assumptions; rather than acting the way you think is correct.

If you aren't their personal dev, then don't be one. The only thing my presence in a client's slack means is that I (and/or the other people from my company in their slack) am reasonable first point of contact. I'm perfectly happy telling them that their problem is not one I can solve (or choose to prioritize), and that they should touch base with <appropriate person>.