How is this fair?

I've been on this website for one day.

And I went to make a trade, but the seller refused because a Mod PM'ed them and said I am a scammer.

I've never been on this website before. How is this fair to me?

If whoever said this can let me know so this can be cleared up, thanks.

Otherwise, it's simply not fair.

 

Unless the person you were trading with provided proof of this PM, then I highly doubt a staff member ever contacted them.

The staff on this site would not message members saying that other traders are scammers without banning them or applying a Trade With Caution rank - I get the feeling this person you were trading with was actually intending to scam you himself, and when he was unable to he weaseled his way out by lying.