Targeting the 1-3% percent of developers willing to work on Linux doesn't make much commercial sense.
You're confusing developers with generic end users/consumers. Yes, Linux has a low market share among the general population, but it's quite popular with people who write code.
For a lot of things it's important to have a decent terminal emulator, a Unix file system etc. Windows has none of these out of the box and even things like Cygwin are a pain to use.
And second, for doing any serious CI/QA-Automation, Linux sucks the least IMHO :) But that might be just the years at RedHat speaking :P