Yeah. My one thought about that is that even if they did chip in, their attacks probably would have done absolutely nothing and made zero difference since Jiren really seems to be complete bullshit. And so if they attacked him, all that would accomplish is Jiren sending Cabba, Caulifla, and Kale flying as well when we broke out and Universe 6 losing four warriors instead of one.
If that's what Hit was thinking -- realizing that once Jiren resisted his attack, it was over for him, and if the Saiyan Trio jumped in, it would have been over for them as well and so he just shooed them away to avoid that -- I get it, but it's still very unsatisfying to not even see them try either way. =/