As per https://internetofcoins.org/en/earlyholders:

AFTER MAKING ADDRESSES

When you have made 7 addresses using the blockchain systems above, please send them to us by e-mail to: distribution@internetofcoins.org

Please copy and include the following in your message.

TXID: {transaction ID's you used}
Omni: {public key}
Ethereum: {public key}
NEM: {public key}
Bitshares: {public key}
Counterparty: {public key}
NXT: {public key}
Waves: {public key}

Could someone please clarify how such submissions would be verified to ensure that the claimant is in fact the original contributor?
TXID-s are publicly visible, aren't they? I.e. - where in this equation is the proof of ownership of the contributor's private key?
Thx