Yes, I think people can say things like "wow!" or "good grief!" or other things in either a quiet voice, or under their breath—or even to themselves. You could portray this in lots of ways, from 'quietly exclaim,' as you said in your title, to actually illustrating it: "What did you just say?" "I said 'wow.'"
I would support your usage of 'quietly exclaim'. It sounds like an oxymoron, but it is really not. 'Quietly shouted' would be a problem, although, I don't imagine too many people would have an issue with 'whispered loudly'. Personally, I like the unexpected juxtaposition of your phrase.
Some news travels slowly, I guess? *shrug* But since it's Bushtaildawriter's first comment and I'd like to be charitable, maybe Bushtaildawriter was thinking about the same thing and found it, completely by accident, while trawling this forum and decided to create an account just to say "Thanks". More outlandish things have happened. Three different guys being the Pope at the same time, for a start.
Ah. *shrug* I wasn't sure if this was a bot, but now you point it out, it sure seems like one. On the other hand, drawing from our discussion of Blade Runner in the other thread, who's to say that charity to bots isn't a virtue? Who knows, this bot might grow up to become a replicant ... (but probably not)
I'd say most likely. Which is why our esteemed moderator asked a question, that a human being would most likely answer, but a bot won't. It's a sort of turing test, or Voight-Kampf (if you remember your Bladerunner lore).
Quest choked back a vitriolic oath as he dodged around the corner, out of sight of the cloying, empty headed perfection of Mary Sue. Cracker Jacks! The woman was a menace to flawed mortals. Huddled behind the moth bedraggle tapestry, he waited until her footsteps faded. Yes, he was common, but no one had every called him stupid.