Yep....A B52 would be flying higher than you could see it, and if you were up in it you wouldn't see the ground. Plus none of the OFP runways are big enough for a B52.
Even so, they carry over 70,000 pounds of bombs, and if you were to carpet bomb a position with one, there would be so much lag as all the bombs go off, you'd be sitting there for a while waiting for it to end. Try detonating 30 satchel charges all at once...a little lag there....now try 30 Mk84 bombs (which are exponentially more powerful than the biggest explosion we have in OFP) all within a few seconds...hell on earth.
Plus B52's don't run CAS missions. They bomb big things worthy of dozens of tons of bombs. They can carry cluster munitions, but that's for like whole divisions caught in the open.
So in short, no, there's really no use for a B52 in OFP.