I can give it a go, but it'll probably be pretty flimsy arguments since I don't have anyone else's ideas to disagree with.
Personal: Pro - Could know where he was, what his habits were (when he was likely to sleep, possibly which end of the tent his head is usually at, how sound he sleeps, etc.), and probably know some of the same things about the BIL. May have a motive that nobody else is aware of, if seen there before the shooting, could pretend to have planned a surprise visit (while hiding the weapon close by). If seen after the shooting, could send people off in some direction saying the shooter had taken off that way (and maybe had dropped the weapon if the shooter is wearing gloves.)
Con - Would not be likely to want to take a chance on one of the girls being hit, (if not the BIL) would be taking a big chance that BIL might come out sooner than expected after the shot and see/recognize the shooter, if the shot missed or wasn't fatal, TB could see the person and at the very least call out their name.
Professional (hit man) Pro - Would probably not worry about whether or not the girls were traumatized, would be likely to have the equipment needed to make the shot, would most likely have been given much of the info that a personal shooter would have, would likely have at least one alternate escape route in case something interfered with the planned one.
Con - Wouldn't be likely to know where he was going to be far enough ahead of time to check things out thoroughly, would probably have to be fairly familiar with the area to make it through the trees in the dark without being seen or injured, would need to make sure the hit was successful (which would mean opening the tent and risk someone hearing the zipper, or cutting the side of the tent which somebody would have seen and mentioned), and nobody has found anything bad to say about TB that I've seen, so it's unlikely someone would put out a hit on him.
Random Shooter: Pro - The other 7 (?) shootings were done close by, it appears to be only one shot in each incidence (I believe it was the ME who said it looked like there had only been one shot), the shootings are during pretty much the same time of day and most the same time of year, with all of the misses (and the one non-fatal hit), the random shooter doesn't seem to care if he hurts/kills anyone, so there'd be no need to check on TB, and he seems to know the area well enough to disappear quickly since there don't seem to be any witnesses that have seen even a glimpse of him.
Con- I'm not sure, but I don't believe there were many potential witnesses in the other cases, seems to use a shotgun all or most of the time, which would have been likely to have everyone outside looking for the source (and made him more likely to be seen), since LE doesn't sound real keen on the idea, a different type of firearm may have been used on TB, and just having the other tent so close by makes it too likely that someone in there might come out to use the restroom, have a smoke, or whatever.
