So...odds of Coulson being the first successful test subject?
(Assuming that they don't want him to make a Flowers for Algernon/Charly-style exit at the end of this TV series, of course.)
If he is, that makes him not just a "liability" to use Hill's word, it makes him a Highly Desirable Commodity.
Coulson debuted with the first entry in the MCU, Iron Man
and has been with it every since. I doubt that they would do that to the character.