It seems to me...
They only control images that relate directly to the Burning Man event.
If there are no identifying features showing that it was taken in part and parcel of the Burning Man Event then you're way free and clear - they do NOT own nor have exclusive right to images of the entire Black Rock Desert, just of their event.
So,,, does that mean if I throw on my Apokiliptika duds and go hang with some fellow apokiliptikans out at Black Rock and shoot some pix, does the llc control those pix? Nope, for even tho the pix were taken at Black Rock Desert (not the city) And Apokiliptika maintains a presence within BRC (our ever-expanding zone of occupation) both are entities seperate from (and not beholden to) the llc for anything other than space and the limitations they put on using that space (their licensing agreement on the back of the itcket)in the area and during the time they control that area.
No more than the llc controls (for example) the footage various and sundry auto manufacturers use to sell their cars in advertisements shot in the Black Rock Desert.
Now... the BLM *may* have some stipulations on how you may use *their* land, but I think it's a non-issue, as long as there's no ifeatures identifying it as being within the llc "zone of Control" (BRC and it's environs)... like the trash fence in the background, using something that was obviously part of Burning Man, Etc.
Then again, the art itself is the property of the artist, not of the llc. Who says the artist cannot take photos of their art and later either market those photos (as long as there's nothing involving the llc, in contrast to just a ref to the Black Rock Desert, in those photos) or use them as part of their portfolio to market their other art (or art conceptions).
I'll give you my example. I'm doing some conceptual art using pictures taken out in the black rock desert of something which *is* directly (and kinda obviously) relaed to the Burning man event but was *not* taken during the event (in fact it was months before) or under the license of a BRC ticket. Does the llc govern those pix? As much as they may like to, they can't - the art photoed was the property of the artists (which was NOT BM llc, btw) on public land, based on an image in the public domain.
It is indeed a sticky legal problem, but it seems that Heli's pix (some of which I have seen and personally think are pretty awesome), which while taken adjacent to the llc event, as long as they were not taken of the event or within the confines of the event (or under the terms of your contract - that ticket you bought) are his to do as he wishes - sell, trade, post, or burn.
As they say... read the back of your ticket. CAREFULLY. Not only for what it controls, but more importantly, what it doesn't.
The above is opinion only, and may not carry any weight whatsoever. It is not construed to be legal advice, for which one needs to seek the services of a licensed attorney. Post no bills. Caevat Empetor. Look both ways before crossing the street, etc., etc.