I have a lot of doubts about any Orion Thornbro link. We are told that this is a ritual landscape and the henges are contemporary with each other. Yet when the Orion theory comes into play the other elements of the landscape are forgotten about. Yes, there is an alignment it is roughly a NW-SE alignment of six henges and a stone row, not to mention the various pits, cursus's and other henges.
Orion rises in Late september in the SSW and leaves us in mid march in the SSE, as we have seen the henges are roughly aligned NW-SE and the cursus is at 90 degrees to the central henge NE-SW therefore one of them is bound to intercept Orion at some point.