They weren't really fail safes. Ergen could have bid for both Sprint and Clearwire if he wanted. The only issue besides raising the bid was the breakup fee. The litigation was already on and even a unanimous Clearwire board believed Ergen was right. If Ergen won, there would be no breakup fee. If he was outbid, he wouldn't be responsible for the breakup fee. Ergen knows both Sprint for Clearwire, and Softbank for Sprint would have gone higher to overbid another offer from him. He didn't raise the ante because Son told him he would have the network share deal he wants.
It makes sense. He waited until SB had control so Son could cement the deal. I bet Ergen agreed to stand down from Sprint, Clearwire, and tmobile in the future to keep the acquisition price down. If Son wants to be number one, he needs Ergens AWS spectrum for millions of new phones. Clearwire Spectrum can carry the data. He also could use Charlie selling to his 30 million DISH customers on the Sprint network like LEAP does to build revenues and better utilize the spectrum capacity. I bet Ergen buys LEAP to advance his Sprint based wireless plan. Maybe he even buys ELNK for his wireless Internet access business infrastructure and the EarthLink customer base.
Yes you need spectrum, However, the more dense the network the less spectrum you need.
So building out the network with small cell or the like in profitable urban areas would make the need for vast quantities of spectrum less. There is some break even point between density build out and spectrum purchases.