I'm just wondering, is it 20,000 BTC, or $20,000 worth of BTC? Because if it's actually 20,000 BTC, that's over $1.5 billion, which would make it obviously a scam. Anything involving that huge amount of money and offering deals like that is extremely risky, no matter how trusted the user seems to be on the forum.
It doesn't matter the amount the person is asking for. Why will I want to do business with such a person in the first place that has a zero rep? So what if it turns out to be a scammer, then who will I hold responsible for such a foolish act if not myself.
Things like this gets me wondering about the audacity of the person. Like who will be so foolish enough as to trade with you?