Why Security Deposit for BTC Seller?

[MnM]

Seller security deposit

Sorry, I would like yet another clarification. A friend is trying to sell her 0.006 Bitcoins and she is unable to post her offer to sell because it asks for a little more than that same amount as security deposit. I have not been able to help her because personally I have never sold Bitcoin on Bisq, but only purchased. So I turn to you: what is the point of having to deposit more than the entire sum you want to sell as a security deposit? She actually loaded those 0.006 Bitcoins to her Bisq, s…