This is why
Timo and others have had to come up with some sort of workaround, usually suggesting the wormhole somehow remains open and connected to the same branch over a period of 25 years. But there a a number of problems with that, including the aforementioned 25 year gap: Why, for example, did nobody report finding a trace of the opening? They must have been looking. And didn't the opening change location for some reason?
Timo's recent effort tries to overcome those problems of course, but as far as I can see, the wormhole closed after the Narada came through so was not likely to be effected by the Kelvin's demise (I guess its hard to spot a black-hole without the proper sensors when nothing is coming out of it of course!

). Anyway the Kelvin would have shielded the wormhole from the Kelvins destruction. Moreover the Kelvin was destroyed some time after the Narada's emergence, so it seems unlikely to have been the reason the Jellyfish was held up. It makes sense there can't have been much time between them entering the wormhole and Spock later describes his trip as having taken only a few seconds. This isn't an issue if we assume discrete time travel events that just happen to come out in different time periods.