Tom, I upvoted this because I'm a fan of the LW "physics for rationalists" series that Eliezer started two summers ago. Interesting stuff.

My uneducated intuition is that you're right, and the graviton is the same naive-hypothesis-extension failure mode as aether.

But it's interesting to note that these two meta instances of reasoning-by-similarity are apparently acceptable:

• "Making a hypothesis about a different physical phenomenon by naively extending common properties of a group of well-understood physical phenomena is bad." (paraphrase)

• "Theories of physics have a known tendency towards elegance and simplicity."