Your unconditional rejection of Microsoft products and seeming unconditional embrace of open source is too biased and one-sided, and also not practical in a large organization where Microsoft whether you like it or not is the preferred choice for a host of reasons, not only security.
Also in this case I'd like to point out that one of the people fired was the Senior UNIX admin, so it appears MS softwarewas not to blame. Also if everyone were to switch to Open source you'd see more malware and viruses targeted towards linux and other threats.
Your passion for Open source is commendable from an ideological point of view, but not very practical
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