The fact that someone even tries to sell the asset that has been offered for collateral is reason enough for a lot of people to mistrust someone... for you two it isn't, OK. But for a lot of other people it is (whether you think it is "fair" or "logical" is irrelevant)...
I'd say: "it depends". Suppose someone needs money quickly, and has collateral that's worth much more than what he needs. He can increase his odds of getting money quickly by taking both paths: try to sell the collateral, and at the same time try to use it for a loan. If he's open about this, and mentions this in both threads, I see no problem with it. [...]
Yes, it depends... and it speaks for you that you actually think for yourself. Unfortunately, "a lot of people" don't...