The argument of the development team having knowledge of Windows is the same as the usual "we're used to it" argument, but with the developer instead of the end user. So, the value of this argument also diminishes when the system is less similar to a typical desktop windows. But maybe the core components used by the developer are the same, and in that case you have a point (assuming there are more windows than UNIX developers).
While I see that you have "add-on developer" next to your username, the quoted section above (as well as a few others) tells me that you've not really done and "serious" coding (new applications, CODECs, drivers, etc).
It goes well beyond programming concepts, or even languages, it gets into development tools, work environment, and also everything else that Helior said.
From the coding side, it doesn't matter how much of the user interface is actually there, that only affects how the application looks to the end user. Everything that the devs use is the same regardless, and that is HUGE.
Further, as I've tried to point out, it's not all about the desktop. Now, maybe I missed it, did they state that they are using a desktop OS? The Windows names applies to server OS's, desktop OS's (which ARE using much of the same code, but are different enough to serve the specific purpose), micro-devices, embeded devices, and real time computing. ....at least. They are all quite different, yet still called Windows. But the arguments aimed at the desktop OS can't be leveled against the embeded stuff.
Also, as for bit rot, EVERY OS suffers that. It's inevitable. Windows (desktop and server variety) has gotten much better about that, and it's not really the issue it once was. Now, when you have an image you can either blow down to the HDD, or even just swap drives with a brand-new image in a matter of seconds, and especially when you still have the issue with every other OS, that becomes a totally moot point.