i think that you're falling directly and catastrophically into the trap set up by claiming cancel culture "ruins lives," which in the context of a comparison to prison is going to be a real issue.

it is not a reasonable thing to compare a person who has their admission to a university revoked with a person who has been convicted of a crime and is, no matter what happens, going to have their fundamental freedoms severely curtailed for a number of years.

a person who has been "canceled" in the way you describe can do almost anything, except the specific thing they've been canceled from. a person who is in prison can't do anything except what the prison allows.

"rehabilitation" in these two contexts is not something that can be compared. from the perspective of a prisoner, a canceled person has already been essentially exonerated. the extent to which you would have to either aggravate what "canceling" means, or mitigate what prison is, in order for the two things to be comparable, means that there's no basis for a claim of hypocrisy. the prison system could be 10000% more rehabilitative and it would not be anywhere close to as lenient as "canceling" is. saying that the former should be less harsh is not in any way inconsistent with not saying the latter should be.

the way you've laid it out, it would somehow be hypocritical for someone to think that their colleague should be reprimanded for stealing their lunch if they opposed the death penalty for murderers.