Trump has changed a lot since his first presidency. He used to be a hardcore fiat supporter, but now he surrounds himself with people who like cryptocurrencies.
I think that if he promises something now he'll feel like there's a debt to be paid to his voters.

Everybody knows Ross deserves a normal sentence. It may be 10 or 15 years, but not life. He was made an example of because the FBI was afraid of people like him: smart, difficult to track tech enthusiasts. They wanted to discourage young people with that life sentence and it didn't work because there are similar markets all around the web. Trump wouldn't risk anything by changing his prison term to 15 years. Prison is supposed to eliminate dangerous people. Those who are unable to live in a society and could continue to break the law. I don't think that Ross is such type of person.