Note the distinction between those things being done in the field of "Philosophy", versus philosophy itself. Note that this:

philosophy really is important, but it is only practiced effectively from within a science

is an endorsement of philosophy itself, though the quote goes on to say that the way that much philosophy is done in academia is pretty useless. So I'm not seeing anything that should generate confusion. When Wei Dai said that the problems are philosophical, that does not entail that the problems should be solved by people with doctorates in Philosophy.

Or, is this just your opinion, not Eliezer's?

While I sometimes imagine myself one of the world's foremost experts on the writings of Eliezer, any non-quoted words are my own.

It just seems that once you pull out all the "science and other fields" what is left has no use for solving practical problems -- including AI.

If you think that logic, ethics, applied ontology, epistemology, and philosophy of mind all have no use in AI, then I think you will find yourself in a minority.