Ed,
I have several pieces of Amboyna burl and have used 4 finishes on them. Lacquer, CA, BLO, urethane.
BLO will not hurt the wood but it does change the color. Having said that, It "seems" like I have seen some very clear BLO, but I have not used it. The BLO I used was somewhat amber in color. And that is the problem I have with it. I love the natural brilliant reds/orangish colors in Amboyna. But slightly amber urethane and BLO (and other amber-ish toned finishes) tint the colors just a tad.
My wife says I am way too sensitive to slight color variations, BUT, amber colored finishes change the reddish/orangish colors of wood to a more burnt color, or change the hue/tint/tone? or what ever into a very slight less appealing color. If seen by itself, one may not notice but when the color of an amberish finish is compared to a piece of out of the same amboyna burl or other red wood with a CLEAR finish such as water based clear urethane, or clear lacquer or CA, there will be a noticeable tint? difference. The water clear finish "usually" shows up reddish colors better.
Amber colored finishes do excellent on tan/beige/brown woods. I especially dislike amber colored finishes on red heart and blood wood as it changes the brilliance of the color.
Other people may have different tastes and like the color that an ambered finish gives. In some cases an amber urethane or BLO might make bloodwood turn from a bright red to a slight burnt red/orange which will match a school color, at which point, it is worth using. I use holly often too. Ambered finishes as opposed to very clear water like finishes will cause holly to look like ivory, which in some cases may be desirable and in others not desirable as the "whiteness" is lost.
One more thing, I use 5000k lighting over my lathe. 4000k lighting does not show up the differences in tones as much as the 5000k lights. 5000k is more like outside and it is easier to distinguish the tint shifts or hue or tone shifts. Noticing this aspect makes pens more appealing.