Any interested programmer can look in the soure code. He knows what he is working with and mistakes in the Linux software are found much easier and corrected.
Also for this reason Linux is more safe. Security gaps are found faster. One more point is that malicious software often is oriented to the popular Windows. But there are more than 100 kinds of Linux which are all different.
Windows was made for an easy usage of computers. For learning how computers are working Linux is better. Unless you want to develop especially for Windows.
The installation of Linux operating systems is easy and for most distributions fast. Open source programms like Firefox are often already there. OpenOffice software, Gimp and more can be installed for free.
Experience with Linux can be an advantage in the job.
Useful links:
why linux is better | http://whylinuxisbetter.net/en/
open source software | https://en.wikipedia.org/wiki/Portal:Free_and_open-source_software
linux kernel | https://en.wikipedia.org/wiki/Linux_kernel
linux distribution | https://en.wikipedia.org/wiki/Linux_distribution
usage share of operating systems | https://en.wikipedia.org/wiki/Usage_share_of_operating_systems