It's on a corridor you have to pass on the way to Astarion, Gale and Lae'zel.
I understand where you're coming from. There's also the issue of being one person down in the fight on the helm. If you play as Lae'zel, you get Losiir, but nothing as Shadowheart.
That said, it's worth pointing out that you don't *have* to pass by those intellect devourers to get to Astarion, Gale, and Lae'zel. You can climb the cliff and bypass that section.
Also, there are generally three intellect devourers there, not just two. I believe it scales down to two if you're alone, but I'd have to double check to be sure.