Is there a plastic cooler and propane heater in there?
But heck, if one wants to use that as a defense, why pick that photo? It's no more relevant to what other soldiers had in other historic situations, than any photo from the period.
If anything goes, as long as it existed at some time and place in the 1860s, one could just show an image of a wealthy person and cover everything. A plantation owner, New York city investor, high-ranking politician, etc., would expect to have a feather bed, upholstered furniture, servants to cook and serve his meals and stoke his fire, his wife and children nearby, etc. I portrayed a former governor once, and complained a hotel-keeper didn't stay to put my bags away or have a servant do it, after he showed me to my room.
I think the larger point is: If a reenactor has chosen a particular time and place to portray, then there will be certain luxuries available and certain things not available. If he knows his history, he should be aware of the difference between what he's doing and what the person he's portraying was doing. In some situations, he may inaccurately be missing luxuries--such as the Abe Lincolns who wander around events with no entourage or privates to see to their needs, despite being president. In other situations, a reenactor may choose to have more than would have been available. To say he's living just as they did is wrong in either case, because the implication is he's living as the person he's portraying would have lived, and not the way some others in the period would have lived.