when you can margin a stock, you can borrow against your existing equity --it is basically the stock broker giving you a loan. You pay interest, of course, but they don't allow margin on all stocks -- some are just too risky etc. In Miller's case, it is just a matter of price, because most brokers allow margin on Miller, but at different prices. Some do it at 3, some at 4 and a few at 5.
As people with margin buy more shares, price goes up etc. As more people are able to marign the stock, the faster the stock will rise. This stock is a good short term investment because of all the news that will come out in the next 60-90 days. As the stock markets tend to price things in advance, it is good to get involved at lower prices now.
Also margins are at the same level as shorts(shortie in reverse???....hired guns, gambling with borrowed funds, running the prices up faster.It is the same as when the Shorts ran the prices down extra fast and farther down...with borrowed stock from their brokers.All in all it helps raise the floor of the stock up quickly ,and makes short covering squeezier.