Can I send you or anyone a signed message in message form too see if it's good to post publicly? Someone trustworthy
As long as you don't share your private key, you are safe. You can share your signed message.
To verify your signed message, the message, the signature and the address are required.
Sharing your signed message does not leak your private key, but can leak your privacy.
If you share it publicly including the Bitcoin public address, people will know that address belongs to you as well as its transaction history, balance, and more. So it's not necessary to share the signed message publicly if privacy is Coiningking concern. Share it to Freebitco.in team in email or any of their support channel.