Let's put it into perspective. Paul Allen is holding $9.5 billion in Microsoft. Paul is worth around $6 billion more than Alwaleed.
That position couldn't shake Microsoft very much at all, much less the wider tech world. Alwaleed's position in Apple and Twitter are, basically, meaningless to affecting tech stocks. Apple is a $900 billion company, nearing the worth of Aramco at this point. Alwaleed's entire worth is $17 billion, barely a drop in the ocean versus tech stocks. Not to mention nobody seriously believes those positions are going to be haphazardly liquidated. If Saudi Arabia manages to seize Kingdom Holdings, they'll most likely make gradual maneuvers.
The big question to me is what the kingdom will do with all the assets they confiscated.
EDIT: I think they'll start liquidating large assets for their http://vision2030.gov.sa/en plan.