My god, is this stupid myth still not dead? This so called bail out was a 2 Mil. € credit in connection with the Thorsten Frings deal in 2004. It was absolutely a helpful gesture, but it certainly did not save the club, which becomes very clear when you look at the complete debt of the club at that time, which was around 200 Mil. €.
It was supposed to buy the club some time but infact it just prolonged the inevitable, which was the near insolvency in March 2005, when everything came down to a vote of the shareholders of the Mosliris investment fond (majority owner of the Westfalenstadium at that time). The two options were either entering insolvency (which would have included the club selling nearly all assets and the loss of the league license) or agreeing to a rehabilitation concept designed by CEO Watzke, which held major financial risks for the fond holder.
They stil voted for the latter, though, which saved the club. In the following years several other parties helped with the financial rehabilitation of the club: The two local companies EVONIK (kit sponsor) and Signal Iduna (official nameholder of the stadium), which payed way over the odds for their deals for years, lifelong BVB supporter Bernd Geske who bought and still owns a huge number of shares or the US bank Morgan Stanley, which granted the club in 2006 a major credit (80 Mil. €) under very good conditions to name a few.
This whole "bail out" story was just an attempt by Bayerns criminal former president to gather some sympathy and make a great headline. Again nice gesture back then, very little impact in the grand sheme of things.
As for Hummels, if he truly thinks it was only a minority who showed dissatisfication today, he needs to have his ears checked. I was in the stadium and there was nearly no one who did not at least boo him everytime he touched the ball. He really handles this whole situation with as little grace as possible.