This doesn't seem to be any different than just using a public node or the mempool space api yourself. Relays log ips
NIP-89 Ephemeral Bitcoin transaction broadcasting. https://github.com/nostr-protocol/nips/pull/476
This tool listens to Nostr relays for Bitcoin transaction events from various relays (custom event kind 28333), decodes them and broadcasts them to mempool.space API https://github.com/benthecarman/nostr-tx-broadcast
I wonder how this would pair up with keeping Bitcoin transactions anonymous and broadcasting them anonymously.
Discussion
This was exactly my concern. Unless the user publishing the event is over TOR or a VPN wth a new public profile and then publishes the Bitcoin transaction ID as an event, this could associate the transaction with a person.