Some of the things that make Spector unique in Marvel would make for great cinematic fare. For instance: not to massage stereotypes here, but the fact that Spector is Jewish should make him more appealing to Hollywood, and would make him a rarity on screen as well. Plus, the fact that he's got a convoluted origin story that involves ancient Egyptian mythology brings in a very cinematic element.
Actually, I think the fact that he's a lesser-known Marvel hero works in his favor here --- there would be a far less vocal fanboyb*itchist contingent when the studio chooses to take liberties with the source material, so the movie could be dealt with in strictly cinematic terms instead of comic book terms.
Moon Knight's story makes for a great Hollywood movie/TV show, period --- two-fisted pulp action combined with ancient mysticism and superhero adventure....what's not to like? The GA doesn't need to know this character at all to recognize that it's a great action-adventure tale.