1. The Developer of such an addon may not have ever agreed to the TOS 2. Google is under no legal obligations to enforce a contract between Facebook and the Fa

1. The Developer of such an addon may not have ever agreed to the TOS 2. Google is under no legal obligations to enforce a contract between Facebook and the Facebook user 3. The TOS applies to the user of facebook, not the developer of DOM manipulation Plugin 4. To the extent the developer agree to said TOS, it is largely open to interpretation if TOS have any legal authority at all beyond giving the ablity of platform operators to ban users for violating them. I.e Facebook's recourse would be to identify people using the plugin and then ban them from the site. of-course Facebook has no desire to actually ban anyone for using a public so they use legally dubious trademark claims.