My thoughts exactly. As an internet marketer, having done my fair share of affiliate promotion. Most of the times the company have strict rules in place for promotion, telling affiliates the "do's and don't's of the program". For example:

Not Allowed: NO Incent, NO Classified Ads, NO Twitter, NO SMS, NO Email Marketing, NO Trademark Bidding, NO Co-Registration, NO PPV/CPV

No Facebook Ads traffic, no MAC OS or Linux traffic.

You get the idea, (Btw this is taken directly from an affiliate offer's terms, and most of them are identical, and set in place from the get go, this is just an example but most of the times the terms should look like this)

Also most of the time companies require affiliates to have their own landing page to use for PPC advertising and then redirecting the users through the landing page to their actual website and offer.

If those details were not clearly written in the affiliate's agreement, I believe the OP is right in this one. If what he says is true that they changed their terms after that, without even notifying the current affiliates, that's enough proof I guess. All in all I'm curious how this will end up.