False. It is "safer" by design, with a far more restrictive security model than Windows has traditionally used.
Is this the standard FOSS tactic of comparing modern Linux distros with Windows 98? NT has had ACLs, which are far better than anything implemented in SELinux (and are pretty much what SELinux is trying to emulate) since 1993, and Vista changed the default system setup so that the user is no longer running as an administrator all the time, which does loads. One could even argue that NT is closer to being "inherently" secure since security was actually given heavy consideration during development, whereas for Linux it was just a matter of doing what worked and SELinux having to be patched onto it to get the basic security models that we've taken for granted on Windows for the last 19 or so years.
If you also use SELinux, Windows basically can't touch Linux, for security.
Saying Linux is "safer" by design is saying that it is "inherently" secure by nature, which is a fallacy. With few exceptions (EROS and other capability based systems) There is no such thing as "inherently" secure software. It's just another term in the FOSS dictionary of weasel words. It's funny because SELinux just barely puts the *nix security model on par with what Windows has had since NT 3.1. And Linux wasn't "designed" for security by ANY stretch of the imagination, so it is neither inherently secure nor secure by design. The fact that SELinux even
exists is a testament to how it
wasn't designed with security in mind. It was designed to simply be a UNIX-like kernel for x86 machines. That's it.
Either way, the default configurations of most distros tell a different tale. 15 Minute sudo sessions, and the OpenSSL fiasco for example. The fact that kernel.org was hacked a few months ago; not sure how that would happen if the system it ran was "secure by design".
Neither system is more secure. Security depends on the user and the people administrating the machines configuration, regardless of the Operating System. (excepting, again, capability based systems)