It's certainly possible that this reflects a preferred resting position, but we were hard pressed to think that, if pronation were possible, that it would prefer to rest its hands in what appears to be an awkward position. After all, humans can rest their hands this way, but don't (not that I'm by any means advocating humans as a good proxy for theropod behavior!) Actually, we think it's really unusual that its hands got anywhere near the sediment to begin with -- though, again, it's known with more commonality in later theropods, we'd've thought the preferred position would be to have the arms tucked up! But you're absolutely correct -- functional studies on early theropod limbs is <i>exactly</i> what's called for...and yup, it's unfortunate that most of the stuff this age is half mangled by diagensis, when good complete arms and wrists are preserved at all...!