Wow, I just listened to the relevant parts of that podcast and I really don't know what to think of Ryan's comments. I have no doubt she's being honest and by a process of elimination she can only be talking about Mulgrew. But I never realized how unhappy Ryan was.
But come to think of it, she wasn't the only one, was she. I've always known the Voyager set wasn't a happy one. Several actors have voiced their displeasure about the show, their character, the writers and the producers. I can't recall if Mulgrew every voiced any criticism, but Garrett Wang has been vocal about not getting to do anything on the show (not even directing an episode). Robert Beltran was incredibly honest during the production of the show about how he felt the show's focus had shifted to only two or three characters and that he too had very little to do. I recall reading interviews back in the nineties given to the official Trek magazine where he clearly said this. It's no wonder that McNeill, Russ and Dawson went on to direct, because they had very little acting challenges on that show.
I personally blame the writers and producers. They must have known about the problems on set. They knew that some castmembers were unhappy (even the fans shared their criticism). They did nothing about it. Mulgrew's behavior was very unprofessional, but I can imagine her underlying frustration.
Edit: Found this quote in an interview in which Mulgrew admits being unhappy and why. She has a point. Still, taking it out on Ryan was unfair.
How hard was it for you, personally, when, in the middle of the show’s run, Jeri Ryan arrived on the set to play Seven of Nine?
Mulgrew: I found that that was hard, Jeri notwithstanding. Certainly, I could see with my own eyes that she was a va-va-va-voom and beautiful-beautiful bombshell of a girl. Sexuality was brought into Voyager, and that’s what I resented. I chose not to use sexuality. I thought that if Paramount and UPN and Rick (Berman) were being exceptionally prescient and brave, they would give a woman a shot at commanding without sex. “Can we do this without sex?” There are always other ways. So I resented that and I was hurt by the immediate, extraordinary attention given to this character. The numbers went up. And I thought, “Ah, you can’t argue with a business decision and you can’t argue with sex.” That’s just part of life, but all of that is very difficult for a woman, particularly an actress like me. But it had nothing to do with Jeri.