Don't you think that "ideological reasons" can be quite a good reason to do things?
Besides, following ideological reasons only means to value certain (other) aspects higher for evaluating the question how good something is.
Usually the term ideological implies (in my book) that a person is considering the greater good, and willing to take a step back in own convenience. That sounds like a nice person to me. Maybe you could spare some curiosity for their reasons?
Sometimes it's because someone wants to leverage the colossal investment already made in VB code and being able to run and maintain it on Linux is better than being locked to Windows anyway.