The only two not-insane candidates they had were John Kasich, who isn't foaming at the mouth and so doesn't excite the base, and Carly Fiorna, who is so invisible the only things I hear about her are former HP employees shuddering at the thought of her being President. I think backing Rubio should be read as "we've given up on having a grownup and are now backing the crazy who might at least take our advice."
Why? I kept reading and never saw her name mentioned once in the Wikipedia article you cited.
The short is that there were multiple leaks that were coming from the board of directors (allegedly). Fiorina started a spy program that went way beyond what a company typically would do, including personal data. She gets forced out and her replacements saw the 'spy' program and said "wow neat!" and ended up in front of Congress.
- The spy techniques that investigators used included pretexting, the use of social security numbers to obtain private records, physical surveillance and the deployment of an e-mail tracer in an email from a fictitious person with a bogus news tip. HP employees were directly involved in some of the methods, according to Holton.