[TheDopp]

2. A "reverse trade" button would be an absolute and utter failure

I'd love to see what post you guys are reading that there's a magic button, or instant undo of all trades ever on a whim. I suggested an opportunity to reverse trades - a possible course of action that traders can go through, meeting certain strict requirements (which will exclude 90% of traders because none of them seem to have the power to read, rules or otherwise).
Given a formal process, with strict guidelines (e.g. proof something nefarious happened), with a team dedicated to security/trading policing, a trader could have an opportunity for it to be overturned. This can be further shored up by the team not acting independent of the community which is not Valve's usual thing. They can engage with SR, or some of the reputable members of the community for consulting.
The true biggest stumbling block is hiring multi language support. With Russia and LatAm being huge markets, it'd be in their interest to not ignore them.