OT: That blog brings me back to 90's web design in the worst way possible. It took me a minute to separate the content from the ads, and I'm still not sure if I actually read the post.
Since Google didn't turn around and immediately release a real-time Google+ search method, I think it's pretty safe to assume that this was entirely business related. It doesn't make much sense for Google to unilaterally kill the feature without having something to replace it.
It's also important to note that Twitter's contracts may not have expired with the other companies, or they were able to reach an agreement that both sides agreed to. Considering that Google was probably using a fairly considerable amount of Twitter's server time(and possibly bandwidth) to make the real-time search possible, I think that it's pretty safe to assume that Twitter wanted more money than Google was willing to pay.
It's also possible that Google wanted more or a better level of access than Twitter was willing to give. Unfortunately, I don't think we'll ever know the exact reasons why this has happened, because of all the NDAs that have to be around the actual contracts.
Either way, I'm still not sure that it's entirely Google's fault. At best, like any business deal that goes sour, both sides are at fault.
How many of those other companies offer a credible Twitter competitor? Twitter's chilly attitude toward third-party Twitter clients makes it seem moderately likely to me that they'd cut off Google's firehouse access to keep it out of Google+.
Do we really know that? Couldn't it have been Twitter which didn't want to continue the relationship?