It's the other way around - if Red Hat wants to contribute to GPL software, they have to reconcile the legal realities of the situation with their business model. If it's not viable for them to contribute like this, then they shouldn't. They're binding themselves to the conditions of the GPL by contributing to it though, and shouldn't be granted exemption for being a business. If sharing their changes out of goodwill isn't their prerogative, maybe they should offer enterprise support to redistribution-optional systems like Minix instead.