I think I’ve settled on the latter. Disagreement is maybe best communicated by the absence of an upvote? And downvotes work best when they signal something that is just off base, and while not reportable, is not appreciated at a broad cultural level.
If I want an article to be read by others, I give an upvote. I’ll downvote if I don’t want it. It has nothing to do with my side of the idea or the event. For example, a rape news was shared. My upvoting does not mean that I support the incident, it just means that it will come to the fore so others can see it.