Good point that Wheeler and Lowe were unlikely to have known each other before the war. Colonel Lowe's having to post a $2,000 bond may have reflected his social status, but it also reflected a concern on the part of General Grant who personally approved his release (possibly over the objections of Secretary of War Stanton) that Lowe might well take the Oath without any intention of living up to its obligations. This appears to be a case of special individual treatment.
The Federal POW records show that Lowe was captured at Whitesburg, Alabama on 11 MAR 1865. He was not captured at the Battle of Franklin nor in the hospitals there in mid-December 1864 when the Federal army was pursuing the Army of Tennessee after the debacle at Nashville. Whitesburg is in Madison County. Lowe was a resident of Huntsville according to your first posting. So Colonel Lowe appears to have been "at home" three months after the battles of Franklin and Nashville when captured.
Thanks for the postings. I will add this to the Society research folder in Colonel Lowe's name.