This is the same country that the US funnels weapons into, and uses for leverage in the region. Does it make the US complicit in the actions that Saudi Arabia does? Now does it make sense to ask for Saudi Arabia to be sanctioned when it comes to business investments?

I think we are arguing it is.

So party A has high standards, parties B and C don't and just trade with each other. Party A withers and and its resources are eventually aligned with B and C anyway. This is not an effective way to fight anything, it's just suicide.

Just quoting @l33tbro <<Well if you want to talk sanctions, I'd say selling them $110 billion in weapons a few months back is slightly more concerning than where they invest.>>

Ok, and if one country does that, then other countries have an incentive to ignore the agreement, and accept all that sweet sweet money.