You're oversimplifying and missing the forest for the trees. By the time the checks cleared with the money in Apple's coffers, it was not needed to keep the company solvent. Jobs had shut down enough departments, and brought the company into one P&L statement, to reverse the finances of the company.

The deal saved Apple because Microsoft committed to Office and IE on the Mac for five more years. That showed enough support to give confidence for consumers and institutions to keep buying Macs. When the five years were over, the iPod was out and Microsoft couldn't afford to leave the Mac.