Where did they mention cost concerns? I’m reading this that it’s an IT/procurement hassle dealing with the Windows Pro upgrade licenses, on a platform they don’t feel is secure, not a cost issue.
They also mention multiple times that Linux and MacOS are free, as opposed to Windows Pro - which can reasonably be read as „we don’t want to spend money here“, since otherwise you could just strike these arguments and revert to „we don‘t believe Windows Pro is secure“, which incidentally they never say.