Petitions are meaningless exercises in self-importance. File all the petitions you want, but no one, anywhere, ever, is required to give them any weight. The only thing a petition does is show that people are interested in something. Whether the people you're petitioning act on this request is entirely up to them. No one can compel them to do what the petition is asking them to do.
Just because you wrote it down and got 10,000 signatures doesn't mean you can change the world. All you've proven is that 10,000 people know how to sign their name.
Occassionally someone might care enough to listen and you'll get that TV show back on the air or that DVD box set released, but 99% of the time it's not going to happen because it's not cost-effective. Companies have whole departments dedicated to figuring out ways to make more money. A guy sitting in his living room is not going to think of a release these company people haven't thought of already. Chances are, if it's not a planned release, it's either been shelved or outright rejected. This could change in the future, what with trends ever-shiftings, so the moment the company smells a money-maker, they'll jump on it.
As for Queen, they'll well aware of what fans want. A petition will do nothing. It may even hurt your cause.
You get 10,000 fans wanting one concert, but another 10,000 petition for a different concert. Then a different 15,000 request a box set of demos! Queen Productions, if it even wanted to consider the quagmire of letting fans dictate releases, would then reject all the proposals as debacle waiting to happen.