Yes, state re-enfranchisement procedures fairly enable felons to regain the ability to vote, because it is fair to make sure that felons pay their debt to society before they are restored the right to vote. It would be fair if felons could never vote again, so it is fine if state procedures allow for limited ways to allow felons to vote again.
It is unjust to prevent anyone from voting in a democratic society. Democracy is based on everyone having a vote and everyone participating in society - the principle of "No Taxation Without Representation." Especially in a society that imprisons so much of its population, and does so overwhelmingly to minorities and the poor, stripping the right to vote with a conviction tips the balance toward the rich and those already in power and is against the basic principles of democracy.