Yeah, I'd read it. It's not only an interesting (not to mention fitting) interpretation of Sniper especially pre-canon, but I'm all for reading about him being a creepy pervo. Growing up in Australia as the only one not getting buffed by Australium (and apparently not even being Australian) with just the sheep to call your friends must be lonely. And it tracks that the only beings you really managed to bond with would have considerable influence on his budding sexuality. Also plushophile Sniper is so real, especially with fluffy ones. Maybe the lamb resembles one of his plushies a little too closely and that's part of why it couldn't be redirected, or perhaps the plushies were never really enough for him in the first place and this incident was only a matter of time.

Wouldn't be surprised if that led him to decide he'd be better off alone forever and might as well start getting used to it, practices his survival skills and takes his other violent impulses out on dummies set up, shooting them with a BB gun and later a hunting rifle to practice his aim. Finds out assassins are a real, viable career option and things steadily fall into place. Wouldn't be surprised if the whole incident with the sheep and lamb was part of the reason his relationship with his parents is so strained. Either he gets caught with the lamb and gets pulled from therapy, as it seems to not be working. Or he doesn't get caught and that encourages Sniper to go further, teaching him he can give in to his urges as long as he doesn't get caught, eventually does get caught when he's several years older and gets kicked out, travels the world and becomes everyone else's problem.