Certainly he has made a career of acting like one. But is he, truly, a moron?
He is letting dollar slide, for one thing. That has the effect of raising the prices of imported US consumer goods and lowering the relative cost of domesticly produced consumer goods. Still, is there a palpable difference? Econo-Girl posits, and she wouldn't be the first one, that the deliniation between the two blurred a long time ago. Japanese cars are made in America, after all.
At any rate, to the extent it applies, the huge consuming machine that is the US public gets its US-made goods cheaper and it foreign-made goods at a higher price. Not a bad choice for a President.
Secondly, the low value of the dollar puts pressure on China to revalue its currency. China won't, of course. But it is a bit like tightening the thumbscrews on them, knowing they could leave at any time, but won't. Since China has a lot of dollar holdings, it then becomes their immediate priority to float loans to the US to inflate the dollar's value compared to the renminbi. So we can keep our prolifigate spending and the Chinese can keep their currency peg. Both goals seem to be of dubious value. But not a stupid move by Bush.