I agree. "The Bottom Line" is not formulated as well as it might have been. It is possible to come away with a literal understanding like yours, which is wrong in important respects.
((edited here) There's no point in discussing what the post "really" means. Its only function is to transmit ideas to readers. People's understanding of it may be a map, but it's the map we care about here, more than the territory.)
In the spirit of contrarianism, I'd like to argue against The Bottom Line.
As I understand the post, its idea is that a rationalist should never "start with a bottom line and then fill out the arguments".
It sounds neat, but I think it is not psychologically feasible. I find that whenever I actually argue, I always have the conclusion already written. Without it, it is impossible to have any direction, and an argument without any direction does not go anywhere.
What actually happens is:
It is at the point 3 that the biases really struck. Motivated Stopping makes me stop checking too early, and Motivated Continuation makes me look for better arguments when defective ones are found for the conclusion I seek, but not for alternatives, resulting in Straw Men.