Refusing to federate with Threads would achieve exactly that outcome. Most people on Threads wouldn't know the Fediverse existed any more than most people on Google knew XMPP existed.

The Fediverse is struggling to get a large enough userbase to be as useful as the mega-services it replaces. Threads can gift that userbase and make people more aware that the Fediverse exists.

FWIW this is exactly why Threads didn't join the Fediverse until they'd overcome the legal obstacles to operating in the EU. If they'd federated first they risked losing all their potential EU users to the Fediverse.

The quickest way to lose this game is not to play it and the Google/XMPP example iillustrates why.