"Which, quite frankly, is perfectly rational if you know anything about the technologies involved and have actually had to administer them in the field."
You are coming across all "Trevor's Way or Highway", when in actual fact the world doesn't revolve around Windows, as you well know judging by your articles at El Reg. I'm quite happy for you to state you think there are no options, but I have seen cases where there is no option but to move off Windows. I would agree that Windows & Open Source have closed the gaps a lot over the last decade - but in my view that is making them *more* interchangeable not less.
"It is absolutely a safe assumption to make that Windows --> Windows will be easier than Windows --> Linux with a one month timeframe remaining on the clock, because the number of instances where Windows --> Linux is easier than Windows --> Windows is irrelevantly small to start with."
We can argue about the scale of the last category 'til the cows come home, but the point is that category does exist (albeit most of the low hanging fruit has long since gone), which is why I said it's a mistake to *assume*. There are quite a few businesses out there that couldn't exist without taking the Open Source route.
It's not an Windows or Linux equation, Open Source has grown more through opening up new markets than cannibalizing Windows market share - obvious examples being bits of iOS & Android.
"If you can't accept that simple fact then you don't belong in IT."
I am sure that I don't "belong" in the form of "IT" that you are espousing at the minute, and I am quite happy not to "belong" to it.
"You should be out founding religions."
Nah, I'll leave that to Steve Ballmer, he's done a far better job than I ever could, and I could never make the line "Developers! Developers! Developers!" as memorable as Steve did.