Actually you're understanding on this subject is flawed again. It's not Tizen that allows Android apps to run, it's ACL and it's a very important distinction since ACL is not specific to Tizen.
"OpenMobile's ACL? enables 500,000+ Android Apps to run on any device (Smartphones, Tablets, eReaders, Connected TVs, In-Vehicle and In-Flight Infotainment) and any operating system (Tizen, MeeGo, webOS, Bada, Windows, Linux, etc). An OEM launching a device that does not offer a massive number of apps faces the lack of customer adoption. With OpenMobile's ACL? technology, you have the power to choose. You choose the device. You choose the operating system. OpenMobile's ACL provides the full App ecosystem."
ACL? for OEMs - The Power to Choose.
Honestly Ubuntu Mobile could run ACL and be a more compelling mobile platform then Tizen. But keep in mind they have yet to really prove how well ACL is going to work in the real world.