Craigl, that is a reasonable solution if you are under deadline. Just be aware that this problem has nothing to do with WordPress. The pattern that is being filtered against here can come from any type of software. The code in question on my site is custom code that has nothing to do with WordPress. And if you host another site that makes a series of POST requests on https connections it may fail as well.
This is a hosting provider configuration issue from what we know so far. Not to their fault - they deal with a lot of sites that get attacked and they need to be proactive about it, but it requires a bit more fine tuning obviously.