While I agree with your statement, I'm also dealing with on-going non-stop problems with them over the course of the past three months. I honestly wasn't too surprised that they found yet another reason to shut something down. So I've been scrambling to figure out how to keep things up until I can transfer away from them completely.
Either way, I do think for all of the useless emails that hosts randomly send to customers, something like this (when they supposedly are up to date on technology) should have been noted since the 3.7.1 launch. If HG, or any host for that matter, was going to be unable to keep up with the new WP configuration, they should have informed users otherwise, not just shut down every site they host that's using 3.7.1 claiming it's a MySQL/TOS violation.