Speaking as merely an observer and an east coast non-baja guy and definitely not as any kind of a NORRA representative: ok, that sounds like it would reduce costs for the racers and the rules would be pretty easy to write, but my question is "How do you police this rule?" Do any other desert racing organizations do this? Because from my perspective (again, an east coast non-desert racer) it seems like it would be impossible to keep track of who went out into the desert.
In rally in the US, we have an equivalent rule prohibiting any practice or scouting on the roads 90 days in advance. But these are very well defined roads, often with gates, and limited access, and people living on the roads leading to the stages that would see anyone driving there. But man... the desert is just so... BIG!
There's two steps to figuring out the answer, I guess: first, figure out if it's possible with unlimited resources. If it is, then figure out if it's doable with the resources NORRA has. If either the first part or second part ends up at "No" then the issue is moot: it would only lead to rumors and bad feelings of people who were thought to have pre-run, might have pre-run, were seen pre-running, or were heard about pre-running from a third party.
It might be easier just to promote the idea that it's not needed. I don't think Octavio pre-ran, and Gilkey certainly didn't, so there's your top two bikers.