Theres no reason 1 neg should wipe someone out, no matter how new it is. If someone has done a big scam then every DT user would tag them and wipe them out anyways.
There might be reasons. For example if a long standing, highly trusted account gets hacked, it's useful to get the warning (orange color) after a single feedback, as that can be quickly left.
The triple question marks is to give an early warning indicator of a potential long con, so that a scammer cannot continue scamming with the same efficiency as if they still had "green" trust.