The pdf seems to completely ignore that in the past, security researchers have written patches for Microsoft operating systems as a stopgap until MS could get its shit together and issue their own security updates.
I also take issue with the comparison to cars.
If you want to drive a car on the road, it requires a safety inspection, no matter how old it is.
WinXP, even patched, is the equivalent of driving around a rust bucket with bad wiring and bald tires.
It's an accident waiting to happen.
About the only thing I really agreed with was this:
For these reasons, Microsoft Windows XPâ(TM)s end of support, combined with a collective action problem stemming from individual usersâ(TM) failure to realize or internalize the costs of not migrating or upgrading their operating systems, could prove catastrophic.
The problem is definitely a failure to internalize the costs of running out of date software.
That's why the police fine people for having broken tail lights or other obvious safety issues.
There's no internet equivalent, but I don't see why this is Microsoft's problem.
Sometimes you can't convince end users there's a problem that needs fixing unless it causes them pain.
MS needs to pull the plug and the chaos that follows will sort itself out fairly quickly.