A lot of people took this to mean the API was going to keep running.
This isn't strictly a lie, because the person who says this genuinely believes it. But the problem comes from, he doesn't stick around to follow through. Maybe he gets promoted. Maybe he's the "acquisitions guy" and he's gone onto the next juicy startup to tell them the same thing.
The guy you actually end up working for doesn't care about your startup. To him, you're just employees of the firm who got hired a slightly different way than the Graduate Trainee Fast Track Programme he came in on, and it's not that he resents you as outsiders or anything, he just doesn't see why you shouldn't be treated and act the same as everyone else. And since you work for him now, you vote either way with your feet.