On a hypothetical US-based online forum in TTL’s 2019, arguing, say, that past interwar US policies (either in Canada or in Utah) were flawed and contributed to the SGW-era revolts wouldn’t get someone banned.
But making a serious argument for the secession of any part of the Union probably would get someone, if not banned, at least kicked.
Anyone who appears to be apologizing for past terrorist actions by anti-US groups would not only get banned, but would also likely (depending on what was written) get reported to the Bureau of Investigation by forum moderators.