(Incidentally, if they hadn't made this Louis straight, they could have had him kiss d'Artagnan during their imprisonment and then react exactly as he does when d'Artagnan refuses to execute the guy for him. Though I guess if this Louis were not straight fandom would then complain that the sole gay character is behaving badly and is too effeminate etc. etc....)

For this reason alone, I'm glad they made him straight. The sheer level of fandom WTFery if they'd made him gay and terrible would have been...unpleasant.