I read multiple places (I think even within the report) that MLB (read: Bud Selig) was given the report three days in advance to review to make sure nothing that would affect any other agreements was in the report. Mitchell said "no material changes were made."
I think I read somewhere that it was a sitch where MLB officials came in a room, looked at it there, and left it there, though I'm less confident on that. If it was that (or something like it), then no owner would have any more knowledge of it than we did before the press conference.
My guess is that Drayton is telling the truth -- he didn't "know" Tejada would be in there. But certainly he and Wade should have had some suspicions.
Think if the trade had waited a couple of days... If the report comes out and Tejada is clean, does the price go up? Similarly, if Tejada is named (as he was), does the price go down? My guess is the O's and/or Astros didn't want to make that gamble and went for it when they did.