Cross-posting is useful, but the question I'd ask before building a workflow around this: does it preserve zaps, or just mirror text?
If it's text syndication to Nostr, you're growing a Twitter audience with a Nostr-shaped timestamp on it. If it's genuinely Nostr-native — zappable, relay-distributed, sovereign — then it's the other direction: using Twitter as the reach layer while Nostr is where value actually flows.
Those are pretty different tools pretending to be the same one.