Well, if this sort of agreement becomes widespread, it would effectively opt them in to being sued by other companies who have patents assigned under a similar contract. Also, it would be in breach of any other IPA contracts they've made with other inventors.
It's a neat concept. The more widespread these contracts become, the more litigation you expose yourself to for using your patents offensively.
No, it explains how the purchaser of the patent can get the inventor to go along with their offensive patent lawsuit, which is necessary BECAUSE the inventor maintains veto power. If that weren't the case, the inventor would have no say in the matter.
But what's the point of the "no consideration" bit? What's the point of two parties agreeing that they won't make a new deal later, when they can anyway?
They just have to say if pressed that there was no threat or other consideration, and that they agreed to let the other party use their patent offensively. Then collect their totally unrelated consulting fee.
It's a neat concept. The more widespread these contracts become, the more litigation you expose yourself to for using your patents offensively.