Hmm… the guy has the fork sitting at his home, and it clearly says on the fork that it has 6" of travel. Unless Bikeroom sent him some Manitou Sherman knock-off, I think the guy is right. Just believe him already…
As far as reducing the travel goes, I wouldn't suggest doing so. If you're talking about BoyBoy's Sherman travel reduction modification, his Sherman got busted not too long after he made the mod. A lot of people who've ridden the Z150, another 6" SC fork, claim that it the additional height over a 5" fork isn't that noticeable. Have you tried riding the fork yet? Perhaps it's not as high as you think it will be, and you just may like the ride.
If you're completely against a 6" SC fork, then get a refund from Bikeroom and look for a pre-2005 Sherman or reconsider your options. That sucks about your situation.