Ronnie Hillman's addition isn't a pre-emptive strike.
The Cowboys didn't sign the running back as insurance for the impending suspension of Ezekiel Elliott. This is about finding a potential replacement for Lance Dunbar and helping the coaching staff manage a heavy training camp workload at the position.
Speculation that Hillman's signing is directly tied to Elliott's status is understandable, but not substantive. This isn't a sign that the Cowboys expect the NFL to hand down a ruling before the week is done. Club officials have no idea when that hits.
But keep this in mind: why would the NFL keep its investigation into Elliott open for 13 months then decide to drop the bad news in the days leading up to the Hall of Fame induction?