Agreeing with Crimson Fox ...
Your company probably has policies that only support certain browsers.
While Firefox is usually "safer" than Internet Explorer because Firefox does not have the level of access into the operating system that Internet Explorer does, there are limits on what your company "security guys" are authorized to support, due to many factors, including their level of support certification and the company's political/economic structure.
Check for information in your company manuals and memos ... they are probably more revealing regarding this issue than any web search will be. Facts do not always drive company policies.