1/ People keep tweeting this silly thing as if it's some sort of fount of wisdom. It's not -- it's designed to stroke your prejudices, such as blaming Microsoft for their moral failings. 
2/ Almost all of the major anti-virus products today had their start before Win95. Indeed, McAfee had already left his successful eponymous anti-virus company before this "inflection point".
3/ As an "operating system" exposed to a public "internetwork" full of sociopaths, Win95 was relatively secure compared to the systems that came before and after.
4/ That's because Win95 exposed relatively few ports (low attack surface). Unix and WinNT systems had a much bigger attack surface. Network worms plagued Solaris, Linux, and WinNT -- but largely ignored Win95.
5/ The real "inflection point" was BSD 4.2's addition of the TCP/IP stack in 1983. Unix was designed to be standalone, not networked. The Morris Worm exposed the weakness of this design in 1988, and Unix systems really didn't clean themselves up until after the year 2000.
6/ Sure, some things happened on Win95 more than other platforms, like the Melissa virus of 1999, but that was a function of the applications (Microsoft Word and email) rather than the underlying operating system.
7/ The point is that Geer's "wisdom" largely is a system of stroking our prejudices that we are the chosen, gifted with a special insight, not like the plebes who use Microsoft products.
8/ Several commenters to this thread claim Unix was prepared, because it had multi-user access designed in from the beginning. This is nonsense. That's only for terminals connected to serial ports. Processes listening on network ports were almost always run as root.
9/ The Morris Worm got root via the sendmail and finger exploits because those services ran with root privileges. Only in the last decade have people learned the lesson and started dropping root privs.
10/ The only system that seriously "got it" was IBM's mainframes, where owning the TCP/IP stack still doesn't give you root/kernel access to the machine.
