As I said, my general policy thus far has been to just avoid the situation. I've only taken two clients off of Upwork and I've worked with both of them since this was oDesk, so needless to say, we're past the time period. Most of my work falls in the 20% range, and I've felt encouraged to seek work elsewhere for that reason; it was more reasonable when it started at 10%.
That aside, I am particularly wondering about Situation 2 and 3. A client that I did work for provides a service that another client I know could use, and I was thinking of connecting them. I don't see how this could logically be circumvention, since the rule states the relationship between freelancer and client, and I am in no way monetarily benefitting from this arrangement.
Situation 6 also seems to be a safe one, but some tinge of doubt, yet the official reply is that it is forbidden.
Is the official response here just a blanket "safe" reply? Or are these situations really ambiguous?
My two cents...
The enforceability and validity of a non-circumvention agreement really comes down to whether either party wants to enforce one via taking the other party to court in the hope that the jury and/or judge agree with their interpretation of the agreement with an enforceable decision. That is far from a certainty even with the most carefully crafted non-compete agreement.
If both parties live in the same country, going to court and enforcing a judgment can be expensive. Across international borders the cost would likely make formal enforcement very expensive - probably far more than the value of the average Upwork project.
However, unlike most parties to a non-compete agreement, Upwork has the advantage of being able to unilaterally address perceived infractions of its rules without having to resort to going to court, so it's best to be safe and stay out of any gray areas if you want to continue to use Upwork's services.