I totally agree that it's right to go to rocks in certain situations.
Let's keep running with the Greece F6. There is no way until hell freezes over that any Helios would have a shot at winning if Christy or Joanna were in the F3. If we pretend for a second that Rob isn't a detestable baffoon, and say in this imaginary universe that he'd have locked up a jury vote, as well, (and he didn't 3-2-1 himself) it would make ABSOLUTELY NO SENSE for Helios to not go to rocks. If a single one of us changed our vote, we would lock ourselves in a scenario where even if we made F3 that we'd be guaranteed to lose. I realize that's a lot of IFs, but this is an extreme case, and many not-so-extreme-but-similar cases would also warrant rocks.
I just know that Penny is going to respond with some "But I would show the jury how great I was, avoiding the tie, and how it was ALL my master plan to..." No. Doesn't matter. Christy and Joanna would've slaughtered any of us in an FTC. Always. Endofstory. Barring Rob being retarded and a potential FTC loser: rocks should be required.
I could see myself going to rocks in specific F6 scenarios or in a switchless merge-round tribal deadlock. (Because defecting on their tribe worked out so well for Penner, Fincher, Candice, Cochran... defecting makes yourself expendable immediately.) Most other situations probably offer a more amenable compromise.