You can request Steam to remove games from your account, but you would have to make a new purchase should you change your mind.
I have sent a request to Steam. They haven't replied yet (there's a note about high ticket volume on the support page), but it's just been a day - I'll probably hear from them next week.
I don't know if you'll get the unc version from BundleStars, though; might be a regional thing.
I asked Bundle Stars support, and their offer was nothing short of AMAZING (yes, in caps - I rarely use caps, but they are warranted here). They apologized that they won't be able to answer my question before the sale runs out, and then gave me the code for free
so that I have a chance of getting the uncensored version, with no risk of losing money if Steam ends up giving me the censored one. That's exceptional customer service!