Yep. Or at least "be-wary of developing applications with dependency to a platform unless you control it, it's easily replicable, or you have a legally binding SLA in place with the provider."
We're seeing more and more of this kind of thing, and people need to realize that you can't build something sustainable by relying on the happenstance goodwill of some arbitrary API provider.
If you have 'free' API access then you are providing some benefit to the web service (whether you know what the benefit is or not), when you have a 'paid' API access you are a customer of that web service.
If you're paying for a service as part of your product, you need to understand how your costs may change over time, and generally you put into the contract language under what conditions and time frames the price can change.
This is one of the essential differences between building products and building demos. Just like an engineer might build a circuit that works to prototype something, they will go back and do all the edge case and tolerance analysis prior to putting it 'into production.' If you've never shipped a product before it can sometimes be a painful learning experience to get these sorts of lessons the hard way.
Relatedly, Right now, what I think we're seeing is a lack of real competition of direct substitutes. There is nothing exactly substitutable for Twitter quite in the way that products ranging from Heinz Ketchup to the Chevy Malibu face real, direct substitutes, rather than a more abstracted category substitute (i.e. Facebook is similar to Twitter, but it's not a perfect substitute). As such, switching costs are higher and it makes development for a specific platform more risky.