[E. Pluribus Unum]

So their terms of service allow them to retroactively change their terms of service?

Lawyers are going to end up owning SalesForce.

[ProtectOurFreedom]

So their terms of service allow them to retroactively change their terms of service?

The approach they use is very common in subscription services and completely legal. Customers accept this. It's been common practice at the subscription services firms I worked for. Lawyers are not going to "end up owning SalesForce." Here is the pertinent clause from the SFDC Acceptable Use and External-Facing Services Policy.

3. Changes to Policy

SFDC may change this Policy by posting an updated version of the Policy at www.salesforce.com and such updates will be effective upon posting.

That link takes you to the top-level SFDC page. You have to then sift through hundreds of documents to see what changed.

[beef]

If it works against guns, they will try it on oil companies, GMO companies, companies whose management supports the wrong pollination, etc. The only thing limiting it is the effect on Salesforce.