There's no real alternative way to do this; The unchecked wrapper is the way nowadays.
Though you might want to give Sendable-related warnings (SE-0302) backed out of Swift 5.6 a read, since we're "softening" the move towards a fully checked model.
-warn-concurrency will be replaced by something with a little bit more fine grained control as we do so, and continue to work on improving the checking model.