'I bought an unusual smoking tipplers tricorne painted gold for 20 keys. Then I was selling it for 21 keys and a guy offers a 22 key backpack. I accept, but he keeps back some items. So it is more like 21 keys. Then he says I owe him 6 keys because the lower end of the priceon bp.tf is 14 keys. I refuse and he says he is gonna report me and get others to as well. Will I be banned?' I know now that I won;t but that's the reason

Nothing will happen.

And he's going on about how I am going to get a trade ban and all my items will be taken away and I will cry...

Just ignore him and put him on your blacklist so he can not join you.
And IF he still is wiiining about it - save his comments as screenshots. And IF a friend of him start hunting you instead THAT is bannable bcs nobody shall interfere in other ppls business.
And a ban is not so hard to take sometimes - it is only a game!

He is a f***ing baby. He paid 22 keys worth of items for a 23 key unusual. If I were you I would had sold it for buds straight or bit more in items. God he needs to stop whinning and grow up and you to chill.

Any case, his report will be rejected. A mod already replied to you that you cannot be banned. And TF2Op has more genuine concerns and really shortstaffed to be worried over this petty thing.

If its anything, till date i have neve heard of anyone getting banned because one party was dissatisfied with a trade later. If that were the case 90% of the players would be banned as eveyone feels that should get more better deal out of it.

Just ignore his incessant whinnig. Nothing is going to happen. Just chill and perform business as usual

Thanks. He removed me. I am glad!