According to Geoff Keighley, Hideo Kojima was locked away from his development team for the end of Metal Gear Solid 5’s development.
Hideo Kojima couldn’t even contact his dev team for MGS 5
You often need security key cards to get into different parts of corporate buildings. They could simply have not allowed him access to certain areas. If he did sneak his way in they could probably fire or prosecute him. He probably didn’t want to give up his Metal Gear/Silent Hill/Fox Engine babies he spent 30 years creating by quitting. The new CEO thought it was best for the company to get rid of Kojima and get out of console gaming. This is because Kojima went over budget on the latest game and wanted to move to mobile games/pachinko-machines.
So perhaps, Hideo Kojima thought the CEO would have a change of opinion at some point if he stuck it through. After Kojima’s firing and the internet uproar, the CEO actually wrote a public apology that was publicized. He said that he knew nothing about the console games. And that had no idea that Metal Gear franchise and Kojima had such a large and loyal following. And that he regrets the way things went down with Kojima.
The company did do an 180 from the CEO’s initial stance when they originally said would no longer do console games. We have already seen the preview trailer of the new Metal gear zombie game. But it’s too late. They fired Kojima and other key members of the team have left under what we are hearing from former staff are draconian rules from this new CEO that was hired in 2014.