Obviously IBM owns Red Hat now and all that. But people overestimate how much involvement IBM has day-to-day with Red Hat. (Source: I'm a former Red Hatter, left last year.)
At worst I'd imagine that IBM's influence is felt this way: IBM expects x% growth and other metrics every quarter. How that is achieved is up to Red Hat's executives. If the leadership at Red Hat decides it can do that with the status quo, then I don't think IBM is going to say "no, you must change the source distribution to fit our evil plan."
The worst thing that IBM has done directly (IMO) was plucking Jim Whitehurst away from Red Hat and over to IBM, but not making him CEO. Whatever reason IBM chose to do that, it wasn't good for Red Hat or IBM long-term in my opinion.