Well, strictly speaking, a retweet without any explanation does on its face mean, "I agree." And, by extension, if there isn't any explanation carving out any part of it that isn't agreed with, that means agreement with the whole thing. But, yeah, "People get lazy on social media," as in regular speech. So I think you are still correct that we shouldn't necessarily assume something negative, especially if there isn't a pattern as there is with certain other people that are the topic of discussion in this thread.