I'm a Unix guy myself, but I'm not particularly convinced with the "unix is god" listing below. Let's see:

Unix can be installed on more types of computers

Sure, but does it matter to YOU and what you plan to build? If yes, fine, if not, then the flexibility doesn't matter.

Managing 100 servers would be easy using Unix

It's easier than Windows, true. Enabling some services is easier on Windows on the other hand.

Accessibility (Unix +1)

Actually Windows wins in accessibility. Exactly because it's a closed system, and a single entity can design a coherent UI and accessibility experience. OS X even more so. Anyway, the majority of users with accessibility issues (impairments etc), use Windows FWIW, and there is tons of specific software available for it as well as devices.

Most people working on Windows Server do it primarily for the money

I don't think so. I've known many Windows admins, and they either don't like unix or like windows better. It's only unix admins forced to administer windows that only do it for the money.

Notebook/Desktop Hardware (Unix +1) Not ideal for Unix (no native terminal)
This is not acceptable (restricts freedom to target other systems)
Can use cygwin but this is a 2nd class option

You can always use a Virtual Machine to developer for Unix on Windows. Some people even do it to developer for unix on unix itself (it isolates every development system, has snapshots, you can pass it around, etc).

Best designed hardware and client OS experience (Apple)

While Apple might have the best designed hw/os experience, Windows is the second best. Linux is a third (for example: everything comes with Windows drivers from it's maker, not everything comes with Linux drivers).

Cannot target Windows

Actually you can. You can dual boot OS X and Windows. You can also run Windows on a VM inside OS X.

Dependency (Unix +1)
If Microsoft goes down
Entire server stack will be left unsupported and frozen

The "end of the world" is a more plausible scenario. You're grasping at straws here.

All invested time goes to waste

How come? Linux/OS X run .NET via the Mono runtime and libs. And there will be tons of third party support for Windows technologies if a company that has the 90% of the desktop share goes down.

If Unix ecosystem goes down
Impossible situation
There will always be a Unix ecosystem
Has already exist around 50 years

Actually most of old time Unixes have died or are in the decline. Iris, HP-UX, AIX, Solaris.

Linux is an exception (although, technically Linux is not a UNIX, it's close enough). FreeBSD also, but a less widespread one.

And after nearly 20 years, Linux haven't got any real traction on the Desktop, over something like 1-2%.

A future were we all run mobile devices without a traditional UNIX is entirely possible (e.g iOS, Windows Metro and Android which has a UNIX core but no other resemblance to what we usually call UNIX), and Linux is relegated to obsolete desktop machines and servers (say, in 10 years).

Timelessness (Unix +1)
Skills learned 20 years on Unix are still relevant today

And half of this is good (some timeless technology) some of it is bad (some stale shit still going strong on UNIX-land).

Windows Weakens understanding

Yes, but the upside of this is: "I don't fucn care how it works, I just want to build my stuff on top, it's not my problem".