The Yemenis also had the first communist-led government, the first socialist state in West Asia after they ousted the Brits and then won out over the Nasserists for power. There are still remnants in the regular people and in political actors of both socialist and non-socialist groups who were against reunification with the north just as there are newer trends and groups against foreign domination in general like and including the Houthi movement and other nationalist-islamic groups (over support of whom various left-wing and social democrat groups had their own splits over. A lot of different social trends and also different political factions with differing politics from that history, including some active secessionist groups involved in various sides in the civil-and-proxy-war.

Which all of this certainly doesn't help the region and its peoples which used to be occupied by the anglosphere stay out of the sights of, led by the US, the largest most violent empire in history whose interests shape global politics, as the apex of capitalist-imperialism grown to its highest stage in the form of global neo-colonialism. It's more of a neo-colonial involvement in an otherwise imperialist-driven regional power struggle for exploitation of resources (Southern Yemen was a big British Petroleum hub), inherited from the previous history, rather than a specific extermination plan of Yemenis in general. And in that it makes more cynical-bourgeois sense.

This is also all why the US previously, as always and many times in other countries and regions, sided with the royalists, compradors, jihadist fundamentalist terrorists, western-friendly regional imperialist powers, and general counter-revolutionary and opportunist forces against any and all Yemeni socialists and any and all national-oriented or geopolitical-rival-oriented social-democrats in every political struggle and conflict and civil war eruption they had. Unsurprising for the neo-colonials to target, alongside their regional imperialist allies, that which had previously for a century been a British colony.