With this message, I hereby transfer to jnhnum the sum of $12.54 out of my checking account.
(Translation, since that's probably a bit subtle to just throw out there: In the process of abstracting money transfers as "just sending messages" your abstraction has leaked critically important details. There's more to money transfers than "just messages", and it is precisely those differences that are why you will not be finding $12.54 from my bank account in your account as a result of this "message" that I have just sent. Your abstraction is not a good one for any purpose, practical or rhetorical.)
Citizens United (the decision that allowed corporations to make unlimited monetary contributions to political organizations) was justified by the first amendment. A check or promissory note is a message, transferring money, and is a form of speech. Where you spend your money is protected free speech.
Your criticism is logically backwards. Transfer of money is not just a message. It is a message, plus some other things that make it also a transfer of money. You can't reduce it to just a message being passed. It is a message, it is not just a message.
With this message, I hereby transfer to jnhnum the sum of $12.54 out of my checking account.
(Translation, since that's probably a bit subtle to just throw out there: In the process of abstracting money transfers as "just sending messages" your abstraction has leaked critically important details. There's more to money transfers than "just messages", and it is precisely those differences that are why you will not be finding $12.54 from my bank account in your account as a result of this "message" that I have just sent. Your abstraction is not a good one for any purpose, practical or rhetorical.)