[whpalmer4]

OmniOutliner is oriented to rows, thanks to its genesis as an outliner, not as a spreadsheet. You can copy/paste entire rows, collections of entire rows, or individual cells, but not columns. I think it is inadvisable to hold one's breath while awaiting a change in that characterization :-)

What are you trying to do with the data after you copy it? It might be feasible to write an Applescript that copies the data in all the cells of a selected column and stuffs it into the clipboard where it could be pasted into another application; I haven't looked to see what would be required to do that, and this is not a promise to do so!