I'm pretty sure that first paragraph is false. Until I explicitly agree to a contract, or "terms and conditions", I am not bound by anything. If a site I navigate to embeds content from another website I am not immediately bound by the terms and conditions of that neclsred site, to think otherwise would invite madness.
Not to mention the fact that terms and conditions are not contracts. I don't think they carry the same weight, although someone please correct me on this if I am incorrect.
I think this is a good idea, but in no way should it be the only restrained game. Others could be time restraints (total time per game and/or total time per move), depth restraints (if they both work off of BFS/similar), and probably many other restraints that those more familiar with the engines can come up with.
Not to mention the fact that terms and conditions are not contracts. I don't think they carry the same weight, although someone please correct me on this if I am incorrect.