OAuth needs to be brought up to snuff before this can be done.

I believe SkyWiki's GlobalSettings.php is not publicly available, but I'm assuming it's similar to Miraheze's GlobalSettings, where this appears to be the problematic code (lines 18–23):

$wgHooks['BeforePageDisplay'][] = static function ( &$out, &$skin ) {
	if ( $out->getTitle()->isSpecialPage() ) {
		$out->setRobotPolicy( 'noindex,nofollow' );
	}
	return true;
};

If so, is there any good reason not to replace the hook with $wgNamespaceRobotPolicies, a built-in MediaWiki configuration variable?

$wgNamespaceRobotPolicies[NS_SPECIAL] = 'noindex,nofollow';

Seems like that would accomplish the same purpose.