I think Eliezer is suggesting that all the things you've mentioned that distinguish Quinean naturalists from other philosophers are similarly basic, and that "LW-style philosophy" takes (what turns out to be) Quinean naturalism as a starting point and then goes on to do things that no one working in mainstream philosophy has thought of.

In other words, that the problem with mainstream philosophy isn't that it's all wrong, but that much of it is wrong and that the part that isn't wrong is mostly not doing anything interesting with its not-wrongness.

(I make no comment on whether all, or some, or none, of that is correct. I'm just hoping to reduce the amount of talking-past-one-another here.)