My objection is that it's not necessary and that it makes it very difficult for anyone else, in case another person wants to interact, to jump in. There's no need to tie three different people's responses together in one post.

It's not an isolated scene, either. They're all responding independently of one another.

I might not like collab posts, but I can say what they're most suited for is isolated sequences with low numbers of characters. I'm not saying that Forneus should be able to interject between each comment. But this scene is not isolated and three people independently reacting to something does not seem suited to a collaborative post.