No, I didn't express myself well. I wasn't telling you to mark it as obsolete, I was asking why it wasn't obsolete because I didn't realise the other extension is premium, but you've answered that question now. Unfortunately I am doing this for a charity for free and the aim is to restrict the costs to the hosting provider charges, so I can't introduce any paid-for software.
It's not totally clear to me and I haven't tried it yet, but I assume that I can run the Flarum SSO extension & WP Flarum plugin alongside a WP OAuth Server plugin and they shouldn't interfere. That seems logical at this point, since the two WP plugins will have different endpoints that their clients will call. Have you tried that?
