Blues understand Green arguments but aren't persuaded by them (presumably because they have counterarguments), whereas Greens don't understand Blue arguments and this makes it unlikely they have counterarguments.

This is a restatement of the hypothesis under discussion. (That inability to imitate convincingly is caused by lack of understanding.)

your third objection amounts to "sometimes the people defending the incorrect position are homogeneous, this gives them a large advantage in the test".

You've failed to imitate my position. My third objection is about irrelevant detail, not homogeneity. (Perhaps you can suggest a better way I could have put it?)

your opponents' position really has no logic to it beyond saying anything plausible-sounding that backs up their conclusion

Again, you've failed to imitate my position. For concreteness, let's take Christopher Monckton as an example. It's not that I think he's saying "anything plausible-sounding". His arguments have a logical structure which is imitable but they are embedded in a rhetorical structure that I would find very hard to imitate convincingly due to lack of practice. (I guess you could characterize this as a form of irrelevant detail and merge it with my objection 3 but I think these two sources of irrelevant detail are sufficiently different in origin and aim to be worth separating.)