The alternative possibility - that the scientists really are smearing the opposition with no good reason - is far more likely, and thus the net effect on our posteriors is to reduce them

This is reason why Tyler's argument for a positive Bayes factor is in error, not a reason why my characterization was inaccurate.

Tyler isn't arguing for a positive Bayes factor. (I assume that by "Bayes factor" you mean the net effect on the posterior probability). He posted a followup because many people misunderstood him. Excerpt:

I did not try to justify any absolute level of belief in AGW, or government spending for that matter. I'll repeat my main point about our broader Bayesian calculations:

I am only saying that #2 [scientists behaving badly because they think the future of the world is at stake] deserves more than p = 0.

edited to add:

I'm not sure I understand you're criticism, so here's how I understood his argument. There are two major possibilities worth considering:

1) "These people behaved dishonorably.

and

2) "These people behaved dishonorably. They must have thought this issue was really important, worth risking their scientific reputations for.

Then the argument goes that the net effect of 1 is to lower our posteriors for AGW while the net effect of 2 is to raise them.

Finally, p(2 is true) != 0.

This doesn't tell us the net effect of the event on our posteriors - for that we need p(1), p(2) and p(anything else). Presumably, Tyler thinks p(anything else) ~ 0, but that's a side issue.

Is this how you read him? If so, which part do you disagree with?