dude I can't disagree more it absolutaly makes sense from a fluff stand point. In the fluff description for the WGBL it says that the Wolf Lord chooses these fine marines from the best of his Wolf Guard. not a direct quote but... how about a scenario Wolf Gaurd is issued a heavy weapon, wolf lord chooses said marine to help hi, lead the force, you get a heavy weapon carryin' WGBL. It does corespond with the fluff, I have to say though I have had quite a few eyebrows raised whenever I field him.
Fluff and rules are two different things, plus even fluff wise it doesn't make much sense. I've never heard of a Space Wolf leader toting an Assault Canon, and it doesn't add up. A leader needs to lead, a heavy weapon trooper has other obligations, its an unnecessary mix of roles plus its not Wolfy, would a Space Wolf leader really sit back shooting things when there's a good scrap to be had at the front line? I doubt it, even Long Fang Pack Leaders don't cary heavy weapons and if anyone did you'd think it would be them.
But fluff aside from a rules perspective its beyond rediculous. They are two different entries entirely, allowing Battle Leaders to take weapon options from the Bodyguard entry just doesn't make much sense and stinks worse than blue cheese (bad pun I know). FAQ or no FAQ I won't run any heavy weapons on my WGBL's it just doesn't make any sense fluff wise or rules wise.