Whether or not it was her idea, I don't believe her asking the administration warranted firing.
I will say, however, that there are several unknowns here. It's quite possible there are underlying issues here.
On a related note: When I was in high school I often felt that I did not have a voice. Policies were put into place that were poorly constructed and never explained and punishments for violating those policies (even inadvertently) were often very serious. Once, a student lost her exam exemptions (straight-A students didn't have to take EOY/EOC exams) because she had a butter knife in her vehicle that was discovered during a random vehicle search. The policy supported the punishment, but anybody with an ounce of logic could look at her record, realize it's a damned butter knife, and decide that the punishment was unwarranted.
When teachers spoke up for her and spoke to the administration on her behalf, many of us felt like we had representation...like somebody with at least SOME power was willing speak for us when we had concerns or complaints about policy.
So if the reality of this teacher's situation is as reported, that she was just relaying a student's ideas to the administration, I laud her for speaking on their behalf. Many teachers don't...they just shrug their shoulders and dismiss kids who have concerns, ideas, or complaints about practices or issues in the school.