Most of the confusion comes from what I believe is a misunderstanding of the powers granted to the central Govvernment and those which are reserved to the states. The United States was originally formed for coorperation between the states and for the Common defence, with the majority of the powers reserved to the States, But the central goverment did have certain powers and responcibilities.

The Constitution said that the central Government was specifically to provide for the "Common Defence". And the exercised that right in the Confederacy by instituting by a draft (conscription) law.

The troops which the Governors were refusing to send to Richmond were for the most part State Troops. Which were NOT covered under those Draft laws. They were for the most part old men and boys who were being used as prison guards and such. State service to my knowledge did not exempt men from the Draft which in 1865 was 16 to 55 years of age. So we are comparing apples and oranges here by condeaming the governors for not sending the troops that Lee wanted. For the most part those men who were subject to the draft laws were not withheld from service with the army.

As for Lee in the Petersburg trenches. Yes he needed more troops. But Lee's army was always smaller than the Union army as was every other Confederate army in the field. YET, Lee was able to send, an entire Corp under Longstreet, to Tennessee. And while in the trenches around Petersburg he sent Early's corp to the Valley and threaten Washington DC. And finally in January 1865 sent some of his troops from the trenches to South Carolina to defend that state from Sherman who the Governor of South Carolina was trying to defend against with those same State troops and prison guards which he had refused to send to Richmond.