You are right, TOS isn't the law. However businesses will try to trick you with this technique, especially if they don't think you have any legal support. You can't commit a crime just because the victim agreed to it, no amount of contracts negate this. Employers often pull this trick to force employees to accept illegal practices.

The person hosting and publishing the code may have never agreed to the TOS. So can't be bound by it. They also can revoke their agreement, and no longer have to comply with it. However, continued use of the businesses web services likely requires agreeing to the TOS and this plug in may be using the businesses web services to make the plugin work.