Media reports say the protests were organised via Facebook. That's possible because ISPs were only shut down on 27 Jan at 10pm. The protests began 25 Jan, which probably mean they were organised a day or two before that.
Beyond possible, it's also logical - protests being organised by Internet provides a motive for shutting down the Internet.
I haven't heard anyone contradict the claim that Facebook was used. All in all, it's credible. (It's information - it's neither innocent nor guilty.)
> these executives haven't used that power
I'm not sure what you're referring to here. You mean the power of Facebook's executive's to impede the organisation of the protests?
Whether they used it or not isn't the issue here. The problem is that they *have* this power. Uprisings shouldn't be at the mercy of Mark Zuckerberg.