Yes, banking laws like Frank Dodd are extremely complex, so complex that I think most bankers don't even fully understand them, but the idea of using float, as I see it, is that banks invest their deposits, typically into mortgages, "agency paper", tax liens, municipal bonds, and I think SunTrust bank was even holding a large chunk of Coca Cola stock on their balance sheet, so banks can hold some equities. I imagine Sokol's acumen is sharp enough to make money even in the limited scope of investments allowable to banks.
I also disagree that Middleburg Bank is too small to compete with the larger banks in its area. Middleburg Bank has been voted "best bank in Loudoun County" for 16 consecutive years. They have over $1.2 billion in assets. Southern Trust closed $1 billion in mortgage loans last year. Middleburg Investment Group has $1.5 billion of assets under management. I suppose if you see MBRG as a small country bank with no real value, it does make sense to sell out to the highest bidder. But it's a solid, well run business, and book value, deposits, and income are growing every quarter.