Speculation is normal, although some of the conspiracy theories are a bit out there, and the talk of this being like 9/11 is a bit hysterical.
But it's the posts saying things like "finding the lack of information tortuous." from people who have no actual link with this other than the fact they have an interest in what happened and "finding it a bit addictive," (not exact words but similar, that show that for some this is a fact of pure rubbernecking. And actually, that's normal as well.... unfortunately.
It must be horrendous for the families who were led to think that the plane had crashed and that their loved ones were dead, to have now been told that perhaps the plane was highjacked and to wonder whether there's a chance they could be still alive, and the not knowing. But I am 
about threats of hunger strike because chances are that if they're not being given information it's because there isn't any information to give.
I think the answer will probably be a lot less involved/scary than the conspiracy theories tell us,. although there's every chance this plane may never be found, in which case it will remain an unsolved mystery and conspiracies will abound for years to come until in decades time someone finds it at the bottom of the indian ocean somewhere.
But I don't think this was about terrorism or threats or anything like that - even if there was a hint of that anywhere security levels would have been heightened at airports etc and they haven't been. If there's one thing we are vijilant about it's terrorism, and even if there's a hint the security services jump all over it.