Governance models not the only reason for fragmentation
Symbian has a governance model and API compatibility testing schemes (on the way for new Symbian Foundation versions) which are aimed to ensure that differentiation of products doesn't become fragmentation for developers.
In theory makers of Android handsets could differentiate anywhere, including common developer APIs, but I don't see why they would want to, it just stops huge numbers of apps working properly on their device. It's a risk in theory, but certainly not Android's weakest point relative to Symbian. From what I hear, Anroid is more likely to fragment badly because Google don't take contributions form other OHA members at all rather than because they use a non-copyleft license and don't have an open source governance model. The other major reason to suspect fragmentation is because operators that use that platform won't want Google taking their business, so will want a differentiated version going forwards and possibly removal of some Google services. You certainly won't be able to get "standard" upgrades from Google on most phones in countries where a network subsidy model dominates.
For me the biggest issue with Android if I'm an OEM or an operator is "do I trust Google?". As a consumer my issues with Android are privacy (Google is spying on everything I do with my phone - I know that's happening if I've got a "Google Experience" device) and, for now at least, battery life. Not being able to go away for the weekend without a charger is a deal-breaker for me on Android and iPhone!
Yes, the Symbian touch UI is far from great and yes it is being replaced with a new version based on Qt. That's going to take more than a year to reach real products though, so it'll be interesting to see how it turns out and how the market develops in the mean time. Developers can start using Qt on Symbian much, much sooner though - it'll be in device firware starting next summer and can be retro-fitted to older devices fairly painlessly before then.