I can see that, but I think the idea isn’t as creative as he thinks it is. A space station is a pretty logical extension of the genre.
I think creative people always overvalue ideas and undervalue implementations. Ideas are worthless. A pair of long-running shows consistently produced to be excellent are priceless.
In JMS’ defence, he was always quite open about the possibility that it was a coincidence and even went so far as to cast Majel Barret in a major guest spot in order to symbolically build bridges between Babylon 5 and Trek fandom.
But when the final DS9 episode came out - a year or two after B5 finished up and featured captain Sisko transcending his physical form in a manner similar but not identical to Sheridan’s final fate in B5 he was very angry and his tone over DS9 soured massively. Not enough that he didn’t pitch a Trek reboot to Paramount a little bit after Enterprise was cancelled, but still.