Once again Harry's voice shrieked "Stupefy!", and later on, when she was remembering this, she could never quite believe she'd managed to do it, but she slashed out with her blade of light like it was a Beater's bat, and hit the stunbolt back at Harry who just barely managed to twist out of the way.
Seems more like just a further Star Wars reference to me.
Well, even if she was somehow protected, note that she was not passively protected (not like a shield spell) - she still had to move to deflect and:
They were both moving slowly, and Hermione guessed that the spell was taking a lot of strength out of them.
So she probably did not have the agility to deflect another shot - especially in the middle of a block or similarly.
Also: A reflected or friendly-fired Somnium could harm neither Harry nor Neville, so there was really little harm in trying - even if Harry came to your hypothesis, he still should have tried it – right after he made sure that she wouldn’t be cut in half subsequently.
As for the other Sunshine soldiers blocking it - I confess that I do not remember how exactly the first-year Contego shields work and what their limitations are (I do not think this has been elaborated upon), but Daphne seems to be out of the main Sunshine cluster here (if there still is one), wielding a sword, as is Neville (so other would tend to distance themselves - they already have, before). She should be quite hard to protect. Of course, there might not be any Sunshine cluster anymore, if Sunshine rushed in-between the enemies, as they planned. But it rather seems to me that that plan failed before it was even initiated. (Their formation is not mentioned in the chapter.)
I confess that I do not remember how exactly the first-year Contego shields work and what their limitations are (I do not think this has been elaborated upon),
They were directional, not particularly large but large enough for one or two people to stand behind, could not be fired through, and had to be maintained with the wand.
The larger versions expand that up to a full sphere that can be fired through and only require concentration to maintain once cast.
It seemed that each hit would drain the shield caster's magic, so your shield strength depended directly upon the strength of your magic.
Update: Discussion has moved on to a new thread.
The load more comments links are getting annoying (at least if you're not logged in), so it's time for a new Harry Potter and the Methods of Rationality discussion thread. We're also approaching the traditional 500-comment mark, but I think that hidden comments provide more appropriate joints to carve these threads at. So as of chapter 67, this is the place to share your thoughts about Eliezer Yudkowsky's Harry Potter fanfic.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six. The fanfiction.net author page is the central author-controlled HPMOR clearinghouse with links to the RSS feed, pdf version, TV Tropes pages, fan art, and more, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: