The only warning along those lines that I have seen was the one that said "Don't post story ideas for Jim to read because he wont read them... blah blah blah".... and well, this isn't FOR Jim. Its for ME.
Yes, but you don't know what his next series is going to be.
And it's not because he won't read them, it's because if he has reasonable access to it...IE, his own fan board...and he happens to come up with something similiar on his own, he can't publish it. One of the major dragon fantasy authors had that happen in the 90's...an entire novel she worked on was rejected by the publisher because it was too similiar to a popular fanfic based on her work that she had never read...but she could have reasonably done so, if it had gone to court. (As I understand it, the fan would never have sued, but the publisher refused to take the chance.)
As such, even though your story likely wouldn't overlap with anything Jim has planned, we have to make a blanket policy against any such thing. We had an unofficial side project, not related to Jim but made of people from this board, some time ago, but it died out due to lack of participation after a few months. You are perfectly welcome to try such a thing again, as it's not on this board....the only reason advertising for such a thing would run into trouble was if there was fanfic on the site (but since that's not the point of what you're doing, it'd be fine.)
Again, you're not in trouble, you just fell victim to a blanket policy that has to be put in place because of legalities.