It looks strange to vanish like that, but he was a fairly new member registered few months ago, and he didn't have any reputation.
I gave him neutral feedback for now, but I will remove it if he comes back and sends you agreed coins.
Before our deal he was looking for a escrow and told me that on simpleX
Why didn't you accept the escrow?
Even someone else with high rank in bitcointalk forum would accept this offer.