I think you have your tinfoil hat on too tight. : )
If Obama was going to send Scott Brown’s National Guard unit to a war zone, why would the Democrats make it look even worse by stalling on seating Brown prior to the announcement? They would seat him quickly, and then Obama would send his unit to Afghanistan. Brown’s decision whether to go with his unit (and leave the Senate temporarily) or claim some sort of privilege to stay behind (and be labeled a hypocrite) would be just as difficult whether or not he already had already been seated. And if Brown chose to go with his unit to Afghanistan, Deval Patrick would not be able to designate a replacement for Brown in the Senate whether it ocurred before or after he was seated.
They probably possess Dick Cheney's “Halliburton Weather Machine”. :)