And I agree with the two of you as well.
Would these explanations be possible?
He talks as if/though he knows a lot. (Perhaps he knows.)
He talks as if/though he knew a lot. (But he does not.)
He talked as if/though he knew a lot. (a past unreal comparison)
Why is #3 unreal?
A: What did the repairman say?
B: He said we had to replace the uppidyclutch.
A: That's expensive. Do you trust him?
B: Well, the talked as though he knew a lot, so ... yeah.