Because prisons can be ruthless places in which many things and people are bought and sold, extending to prisioners the right to vote does present a problem. Prison gangs and/or guards & wardens can use their power to influence how votes are cast.

then wouldn't the answer be to protect those prisoners and find solutions to gang problems rather than "preventitatively" denying people their constitutional right to vote?

Prisons are dangerious but that is not ok. And not voting is not ok either.

Actually, convicted felons lose the right to vote, and that is entirely just.
A completed process in the courts, before a jury, determines guilt, so the felon has had his constitutional participation in the court system, before forfeiting it in the justice system. This country, as you remind us, was not founded to be a hyper-egalitarian paradise of inclusion, nor could it ever develop into one.
That some persons, through choice, choose to attack the common weal, and other citizens, deriving unjust advantage by usurping the powers of violence, of appropriation, and of coercion, (all things vested in the state), demonstrates that they defacto and a-priori reject the state system. So be it. Do not expect to be asked to decide who shall run the entity you have just been convicted of rejecting. That would be more than free lunch, it would be cannabalistic free lunch, eating your law-abiding brothers' freedoms, because you hunger for your own, which you have thrown away. Should you be able to convince a governor or president, you can be pardoned. Expect no more tolerance from the rest of us, and do not create a delusory appearance of yourself as victim. It is you, who are convicted of victimizing us. Kindly bear that in mind, and enjoy your sentence as best you can.

Well. Now that we have come face to face with the realities of life,that unless people are given the right to vote who have been denied proper voice, quailty food, health care, education, housing and economic avenues to wealth accummulation to rectify previous unjustices and get the house in order. And now that the stalling/delay tactics are seen for what they are and you still want to be the only one in control and who is right and the only one allowed to define reality. And now that you have tried to wiesal out of all sanctions against the US through use of the $ and tactics of war, etc. And you want more time to work your work because time is up ... you know like work that work (root) like Pappa Doc. You know so you can be ahead of the game and in a better position to control the market and flow of things...you know so you can set-up a series of events so justice will not roll down like a mighty stream...like a river giving life. Have you ever been in jail or prison ? Or listened to people's stories who have been there ? I have been in jail more than once here, and know first hand the experience of the result of being targeted and profiled; and a series of false arrests and trumped up charges that come so fast that will make you sick if you are not already sick...and paint a picture of you that is false... and then a weave is spun on false information and round and round the web goes. And I am glad that someone else from another part of the world was watching, so the track record of lies could be broken: and I could concentrate on life giving, healing things, rather than death and destruction. You know that someone else could help, because I did not have financial capacity or contacts to fix things before the court date or after the date; and they could clean a slate and check the record etc. in record-time for me and so many others, so we could do business with the world and eat as a people and a country. And even though we as a nation were runninig late, we could still arrive on time or at least arrive period...because I know the realities of life and death and I do not wear rose-colored glasses; and am not in an illusion or delusion or denial because the changes and grief are so shocking and devasting that I have to push them away or repress them so I can keep on functioning...so I can cope. Are you college educated ? Did you you read the primer and classic by William Ryan called "Blaming the Victim".
followed by the Cycle Poverty by others. It sounds as if you yourself somewhere in your lineage have been oppressed in some way, whether you are a have or have not. Perhaps some reflection and conversation with any still living relatives before or since the depression (s) might be interesting. You know, it's like having bankruptcy jubliee for yourself and not giving it to others in other parts of the world who are worse off than you.