Re: "I can legitimately forbid you to copy this message"
I'm not a lawyer either. But see http://www.theregister.co.uk/2008/09/30/reg_ts_and_cs/
"8.1 We do not claim any proprietary rights in the comments that you post on our Website. You agree that you shall be solely responsible for your own comments and affirm that the comments you post on the Website are your own.
"8.2 You retain all your ownership, copyright and other interests and rights in your comments but by posting any comments on our Website you permit us to use, modify, alter, edit copy, reproduce, display, make compilations of and distribute such comments throughout our Website."
And this applies to -readers- of the site: "5.6 You will not use the Website in any manner which violates or infringes the rights of any person, firm or company (including, but not limited to, intellectual property rights, confidentiality rights and privacy rights)."
Now write it out a hundred times before sunrise, or I'll... quote Monty Python at you.[*][**]
(I think that's (1) "fair use" and (2) not actually threatening, also mentioned in Ts and Cs.)
[*] Inaccurately. I googled for Python and "or I'll cut your balls off" and apparently those are the only six words that people reliably remember from the scene, and, to be fair, it's what you -would- remember.
[**] Actually I won't.