You misunderstand the objection. The fact that you didn't expand on your definition of simultaneity suggests that you're missing a lot of background here. There

You misunderstand the objection. The fact that you didn't expand on your definition of simultaneity suggests that you're missing a lot of background here. There are many ways that physics could appear to violate causality with collapse without actually sending information faster than light (e.g. how most of the multiverse theories work).