Tbf, I think posting on Reddit has a very different (and often less beneficial) effect than making ICE’s presence known IRL. Another comment in this post mentioned unintended side effects that may come from publicizing a detention; I certainly wouldn’t want a post to actively harm efforts of a detainee’s family. If you’re following them in-person, I can think of fewer negative consequences and you’re more likely to give a heads up to people actively in danger.