There is one little problem with you theory, shareholders. If the O/S is somewhere around 65M shares but shareholders have let's say 45M tied up and not for sale, then they could only purchase 20M shares. You can't buy what isn't for sale, simple theory.
People get that wrong all the time in a merger, they always think the company should just buy the float and O/S, but they can't. If I don't put in a sale for my shares they can't buy them unless it is outlined in the merger agreement for a fixed price and by a certain date, such as .12 by Dec 5th.