It doesn't (or shouldn't?) take an engineer to understand that this really isn't a big deal.
For an outdoor performance this giant, it's more surprising that Kelly Clarkson didn't lip-sync.
ehhh Beyoncé has this weird stranglehold on people's emotions. Somehow, I doubt there will be too many people griping about lip-syncing (though it's almost a guarantee that she's at least currently planning to lip-sync at the halftime show).
I don't like Beyonce that much and I find all the insane hype around her more confusing than anything else.. But still, my guess is that she'll be getting nothing but praise for how "fierce" she is.