He is available because he lost a senate race to Elizabeth Warren in 2012. Afterwards he joined Fox news as a presenter for the alt-facts movement.
It appears that the main criteria for the post was that he supported Trump early in his campaign. He also supports the insane practice of torture water boarding. This is a technique well known for producing more alt-facts and very little accurate and usable intel.
In short he looks like typical Trump dickhead. Donald Trump should be well represented in this country.