There are no good intentions here. This is the mafia playbook through and through - "It would be a pity if something were to happen to your <insert valuable property or reputation here>".
The important thing is how we go about it, and whether their reputation remains reflective of their actions, or we try and make it worse than it ought to be. We can’t say for certain the author of the message was going to do the latter, but it does not inspire good faith.
It's textbook extortion.
> so telling a business when we’re unhappy and influencing their reputation is the feedback mechanism we have at our disposal.
Telling a business we're going to fuck you up unless you send our friends work, even by implication, is literally extortion.
It's only not extortion if you ignore the extortative parts.
Yes, except this case isn't about a customer—it's a disgruntled vendor (commercial artist) acting on behalf of an association of other vendors. Not (AFAICT) on behalf of real customers.
A customer complaining about their needs and preferences is useful feedback.
A vendor whom you have no business relationship with (and want none) is not helpful.
If they criticize your business practices in public, that's certainly their right. But, if they're threatening to do that, with an attached demand of commercial services to them (or to their associates), that's something else. It's the linked demand for payment that loses them all legitimacy. (Possibly even into criminal racketeering; I'm not an expert).
1.) We don't like your poster so you better remove it or we'll badmouth you within our network.
2.) You have 1 day to comply.
3.) You can instead work with an artist we will recommend (aka connected to us), and we'll cease.
Textbook mafia-style extortion.
However, I’m just pointing out that as far as the implications of the threat goes, in most instances it would’ve just happened anyway, without a “warning”, because people simply post things to make fun of them and mock them. Sometimes those accounts might at least anonymize their subjects, but this might be a name them and shame them type situation.