Neither does Roche do anything. Or Dandelion or Zoltan. I kinda view that as a small easter egg, since that scene really makes no sense. And I don't see why that alone would constitute a "huge disadvantage" for Triss when it comes to choosing between Yen and her.
I care rat's ass if Yenn is official love interest or not. My Geralt will make that decision depending on what kind of character she is. And if she 'disappoints' me and Triss doesn't manage to bring anything to the table, it's perfectly possible my Geralt won't choose either.
Roche is not close to Geralt. They know each other a few days and Roche just needs him to capture the kingslayer. Zoltan and Dandelion can't do anything, considering they are going to be hanged as well. Triss has a close relationship and a very long history with Geralt and then she just let him being kileld by some pricks? She could have easily freed him (there weren't even that much soldiers)
I definitely favored Triss before i have seen this, but now, I don't know. Although I consider to treat this as non-canon because of very bad writing. Books Triss would never just let him just die. Same can be said about games Triss (if we count out this scene) Treating this as a easter-egg sounds good as well.