I have to agree with Tom. In this particular instance, if the situation were about a GLO instead of a high school, I don't see how it could possibly be construed as hazing. Community service is something all members participate in, not just new members. Also, no organization that I know of hides the fact that their members do community service.
Besides, if required community service were hazing, my service sorority, as well as APO, GSS, OPA, and all the other service orgs out there would be based on hazing.
I also think it's a good idea for high schools to require this, but then again, I did join a service sorority, so that's obviously a priority for me.