Why? Honest question, I have no idea. I haven't heard of hushmail in over 10 years, but I just encountered a guy I'll be working with that uses one, I honestly thought they shut down.
Nothing against hushmail. Just seemed funny that after a page of statements about how they aren't doing anything wrong, they use a service designed to conceal their identities. I'm not criticizing them - it's just funny.
I worked at a place that used hushmail for the corporate email. It was a business account, so they had their own domain, but it was through hushmail. So I guess they are doing some business.