If you post a comment on a publicly accessable page, there is an expectation that what you've posted will also be public. That's implied consent and doesn't require signing a contract.

In fact, the EU generally takes the position that a Terms of Service agreement is pretty much worthless. Nobody actually reads those documents, so the terms in them cannot be enforced. A TOS clarifies what a company/organisation will do with user entered content, but in terms of what can legally be done with the data the TOS doesn't apply.