That's probably the issue (for them). Most of the Twitter data is public and so they don't have that exclusivity like LinkedIn or FB. If Twitter shutoff the firehose and made all their data private like FB (i.e. only followers can see the updates and no scrapping allowed) then their valuation might have be twice or more of what it is now. I think companies like Google should be worried about this. Their new suitor can decide to put up wall to Twitter data and put them at disadvantage. Note that doing this doesn't affect their non-tech users because they continue to follow and get updates as usual.
Twitter already shutoff the firehose [1]... and it doesn't seem like that doubled their valuation.
Also, twitter's data was never truly public: you can follow tweets on some topics, but a proper deal with twitter is needed if you want access to the firehose (so it wasn't just under some pay-for-play API).
