Well, he used to be reliable, but long ago.
As a Disney watcher, you can usually guess what Disney is going to do, especially if you're reading info from more reliable sources. Jim has, over time, proposed his presumptions and guesses as inside info more and more so. But good guessing will only get you so far.
Jim also hears things being discussed, but doesn't seem to be aware of how definite or spit-bally those things are. And if it's just spit-ball, those things rarely get re-discussed as "we looked at it and decided we aren't going to do it." And thus, Jim has kept certain rumors alive long after they've been definitively killed or tabled by Disney.
When you're not actively involved with Disney as an employee with them, or an employee of a contractor they use, you lose contacts over time.
I would imagine with the several employee purges that have happened recently, access to inside info will be become even more difficult for outsiders who once had an inside contact.