I guess this is what happens when a teacher comes down on the wrong side of the war on... no, make that for drugs. The admonition, "Don't use Adderall or Ritalin" is for DARE officers to give, not teachers.
I have sympathy for parents and teachers dealing with ADHD, but it does seem that the "diagnostic criteria" have devolved in many parts of the country to a school official saying to a parent, "You should consider an ADHD medication," followed by a general practitioner saying, "Let's try this one".
The teacher fired over her bumper sticker worked at a high school. You'll please forgive me, but I think high school students should be regarded as sufficiently capable to participate in a debate over ADHD drugs. But I suspect that the real issue wasn't so much a fear of a loss of order within the school or students refusing to take medication at the nurse's office, so much as it was their parents taking umbrage or fearing having to justify to their kids why the teacher is wrong.