To put it as bluntly as possible:
Automatically assuming that a GM isn't lying, and that instead, the journalist (who's job security depends largely on them not just making things up) must be making things up seems very stupid to me.
The rumor is based on a one sentence blurb in a power ranking column. It doesn't even directly quote the unnamed source behind the information. It's not exactly the most reliable information out there. That doesn't mean Marc Spears is a liar, but it could very well be that he is running with something that is extremely flimsy at best.
As far as sports reporters' job security goes, they cite unnamed sources in rumors that don't come to fruition all the time. They rarely seem to suffer lasting employment consequences for posting rumors that don't come true.
I can't think of any examples of a major NBA reporter who lost his job over reporting a false rumor.
Just to clarify - all I'm pointing out is that even if you have an unnamed source, you still have to have a source. Otherwise you end up like Jayson Blair.
Is it not more like stock tips, with insider rumors, than actual news? Wrong information is not unexpected since it's speculative in nature, and therefore weak sources are still sources in a sense.
Except sports rumors matter much less and therefore even weaker sources and much less filtering is necessary.