Question was originally much longer, but I lost it with a 'forbidden' server message. I can provide more information if needed, but I retyped it 3 times and gave up. . .
It is useful, but not necessary. Probably all you can do is plane your rough stock. Once you start gluing up the blank, the joiner will tear it up. Most of us use belt and disk sanders.
I find my old craftsman jointer very good at launching a pen blank across the shop at about 100 mph......other than that, it's not of much use in making pens
It's useful to prep a larger piece of wood prior to cutting it down to segmenting size. You do want your wood square and straight before you start cutting your segments to fit together. As said earlier it's dangerous to use on short and small pieces of wood due to the size of the gap the spinning blade is exposed in.