Yes, I understand your logic, I just don't think it's valid. The fact you went away from the Vinted process, IMO, means they are in no way responsible for you not getting payment, and aren't responsible for helping.
And it turns out you weren't being conned at all. Your buyer ended up paying, therefore they weren't scamming or conning you. I understand why you thought that at the time, but calling them a "con artist" after you've received money is unfair. Of course, IMO.