Wasn't Port Hudson used as a crossing point of the Mississippi River in 1863 while Grant was trying to invest Vicksburg? Wouldn't that activity account for some of the men to be in Port Hudson while their unit was in the filed. I.E. returning from Furloughs or recruiting officers gathering up men sent back home for illness or wounds to be return to duty?

We think of Vicksburg as being a 43 day siege. But in fact Union army and navy activities on the Mississippi River and Millikins Bend effectively ended Vicksburgs usage for these crossing months before Vicksburg was actually cut off by Grant's Army which starting that siege. So communications between the 11th/17th Arkansas Cav. and Home would have had to have been through Port Hudson wouldn't they?

Muster Rolls just say that those men were captured at Port Hudson, not why they were at Port Hudson. Which is the question you are asking. I am just postulating that with Vicksburg under heavy attention by the federals in 1863 all such activities that would have normally gone through Vicksburg would have naturally shifted to a safer enviroment like Port Hudson.