This is like claiming that because a coin came up heads twenty times and tails ten times it is 2x more likely to come up heads this time. Absent some other reason to justify the correlation between your friend's accuracy and the current instance, such beliefs are invalid.
If in 30 coin flips have occurred with it being that far off, I should move my probability estimate sllightly towards the coin being weighted to one side. If for example, the coin instead had all 30 flips heads, I presume you would update in the direction of the coin being weighted to be more likely to come down on one side. It won't be 2x as more likely because the hypothesis that the coin is actually fair started with a very large prior. Moreover, the easy ways to make a coin weighted make it always come out on one side. But the essential Bayesian update in this context makes sense to put a higher probability on the coin being weighted to be more likely to comes up heads than tales.
LessWrongers as a group are often accused of talking about rationality without putting it into practice (for an elaborated discussion of this see Self-Improvement or Shiny Distraction: Why Less Wrong is anti-Instrumental Rationality). This behavior is particularly insidious because it is self-reinforcing: it will attract more armchair rationalists to LessWrong who will in turn reinforce the trend in an affective death spiral until LessWrong is a community of utilitarian apologists akin to the internet communities of anorexics who congratulate each other on their weight loss. It will be a community where instead of discussing practical ways to "overcome bias" (the original intent of the sequences) we discuss arcane decision theories, who gets to be in our CEV, and the most rational birthday presents (sound familiar?).
A recent attempt to counter this trend or at least make us feel better about it was a series of discussions on "leveling up": accomplishing a set of practical well-defined goals to increment your rationalist "level". It's hard to see how these goals fit into a long-term plan to achieve anything besides self-improvement for its own sake. Indeed, the article begins by priming us with a renaissance-man inspired quote and stands in stark contrast to articles emphasizing practical altruism such as "efficient charity"
So what's the solution? I don't know. However I can tell you a few things about the solution, whatever it may be:
Whatever you may decide to do, be sure it follows these principles. If none of your plans align with these guidelines then construct a new one, on the spot, immediately. Just do something: every moment you sit hundreds of thousands are dying and billions are suffering. Under your judgement your plan can self-modify in the future to overcome its flaws. Become an optimization process; shut up and calculate.
I declare Crocker's rules on the writing style of this post.