That's exactly why I never submitted a story I wrote to Strange New Worlds. I asked and was told that even if they didn't publish it, I could -NEVER- have it published anywhere else, nor could I even upload it to Fac-Fic dot-com or my own personal web page. That was a deal-breaker for me.
I know people who shared their SNW rejects after rejection. I used to have several of my rejects on my website. John Ordover used to encourage people to rewrite their rejects as non-Star Trek science fiction stories. Believe me, if you'd post your SNW reject to your website, the fanfic forum here, or a fan fiction archive, no one at CBS/Paramount would have ever noticed or cared.