It is not assumed that every users (including root) should see same single Time Zone in one system. So there is basically nothing wrong there.
Specifically in your case, if you want root useing same TZ as EDT, what provents you from changing METDST to EDT?
I didnt logged in as an unauthorized user, but i will try it.
And yes, the default timzone on hpux is edt. I didnt understand why the users during login procedure didnt source /etc/TIMEZONE or /etc/profile. Now i have created /etc/default/tz with MET-1METDST in it, it works.