I think I'll reiterate what I've stated before which is that I think what Josh was going for was to integrate new weapons into the tiers to suit new playthroughs, characters/play-tyles, while not alienating every super powered weapon already available nor being the weakest of the bunch.
So why does Bozar have to be the best long range heavy weapon or suited for end-game?
That's not the problem.
The problem is that the Anti-Materiel Rifle can deal an average of ~880 damage in a single sneak attack headshot, so there's no need to fire more than one round when sniping. Other sniper rifles do lower damage, but higher crit rate and faster firing rate; you lose out on the ability to one shot anything, but the firing rate and crit rate give you superior mid-range performance and don't quite demand a headshot from you. The Bozar? There's no reason to use it. A Sneak attack headshot crit from it will deal ~72 damage and the other bullets just do the basic 19. It's a poor sniper.
On the other hand, it's inferior to the LMG damage-wise. So you're basically gimping yourself for close-range by using it instead of the standard LMG.
Then there's always mid-range, but even there it's usefulness is questionable. Medicine Stick, K9000, Assault Carbine, All American, Survivalist's Rifle....ALL of those are good mid-range options, and even so, mid-range generally means you need a gun that's decent at both close- and long range; it's not so much a stand-alone range.
The result is you have a gun that specializes in absolutely nothing and gets out-classed by someone in absolutely everything.
The only real category remaining is "best all-around gun," for a hypothetical situation where you can only carry ONE rifle, perhaps for roleplaying purposes. I think General Masters said his successful DID playthrough was done relying almost exclusively on the LMG, so it's quite possible, but again, I dunno if the scope would be worth losing all the LMG's extra damage. The problem there is that the Survivalist's Rifle and Cowboy repeater/Trail Carbine/Brush Gun/Medicine Stick are absolutely beast candidates of that category, and you'd have to save up a large sum of money before you could even GET the Bozar. The Bozar's cheap ammunition is offset by it's incredible pricetag, aswell.