I might be too much of a cynic but I'd pay more for it if it was open and in perfect condition. Who knows what you'll find if you open it, neck twisted beyond repair, dead pickups, black hardware or even worse a fender.
In all reality it's probably in perfect condition but what would I do with a box...I'd just rather have it opened.
Unrelated and I'm not at all saying it is the case here but....It reminds me of when I worked in retail in Kansas City. There was a local ring of thieves that was so good at steaming/cutting open boxes and re-sealing you couldn't tell at all they had been opened. They would return the items and no-one was the wiser until the box was sold to another customer. The new customer would open their new laptop/desktop/palm pilot (remember those) and find a perfectly weighted block of wood or brick. Sometimes with a friendly message from the thieves.