That may be the case. But, there have been some news items stating that, before the deal was done, BAC went to the Fed (or Treasury, I'm not sure) and said that they might need backstopping, because Merrill's book was tanking worse than they had bargained for, and if they didn't get it, they would scotch the deal. In that case, the Fed/Treasury's desire to get someone behind Merrill may be a key factor, and now their private guarantee is coming due.
I hope we find out the whole story soon.
Unfortunately, it sounds like you have a point.