That seems untrue.
And of course if Le'Veon signed the deal and was fine he wouldn't have been cut after one year. But what if he had a career-ending injury? Can't imagine the Steelers pay 10 million out then. If "rolling guarantees" are truly guaranteed, then the Steelers would've paid them as a signing bonus or a true guarentee if that's what it took to get him.
And the same situation is true with playing last year. If you could guarantee him that he would have a great year, stay healthy, and be in-demand after playing on the franchise tag, I'm sure he would've played without a doubt. He was more concerned about being protected if the worst-case scenario happened. You can say that you don't agree with him playing it safe, but at the end of the day if he destroys his leg on the first play of his first game now, he gets 25 million. If that happened under the franchise tag, he would've gotten 14.5 million. If that happened after signing the Steeler's deal he gets 10 million. He wanted to make sure that he got as much money locked away as possible for the worst case scenario. Hard to say he made the wrong decision from that perspective.
And before you mention Ryan Shazier as an example of the Steelers "taking care of their own" or whatever, keeping him around is half a million per year, not even close to the cost of paying to keep an unable to play Le'Veon. And honesty, seeing Shazier get hurt and lose out on a massive contract the way he did probably had a role in Bell's decision.