Why not a nexus chipset ?

Usually a reference platform is something for developers and is not widely distributed. With android, the reference platform is a mass market device in the hands of millions of people worldwide. So, if there is a goal of a completely open phone - FaiF all the way through - why isn't one of the nexus phones a natural target for reverse engineering and spec-leaking ? One of the issues with the calypso chipset that I have seen discussed here is what OS to run on the upper layers of the phone - and this is a non-issue, since the nexus phones have been designed from the ground up to run linux. Even if you decline to put android specifically on it, you could run any other variant you like. I am not trivializing the work that has gone into calypso, and I realize that different nexus variants may have totally different baseband components, so you would have to choose one specific nexus model ... but isn't the real difficulty simply the secrecy of the specs of the chipset, and leaked specs solve the problem whether it is a 2G calypso or a 4G OMAP ?