When Florida’s commissioner of education resigned Thursday amidst a scandal over fixing the grades of a political donor’s charter school, we expected some comment from Maine education officials.

After all, Tony Bennett, a conservative education reformer, was the keynote speaker at an education conference set up by Gov. Paul LePage in March, and Bennett was the architect of the controversial A-F grading system that Maine has implemented for our schools.

What we didn’t expect was the response we heard. Instead of defending the integrity of Maine’s school grading program, Maine Education Commissioner Stephen Bowen defended Bennett, suggesting that enemies of school reform had cooked up the charges that toppled Bennett from his post.

“Tony Bennett is a trailblazing education leader whose efforts to innovate and improve student outcomes remain an model for the nation,” Bowen was quoted in a statement issued by his office shortly after Bennett’s resignation. “Reform isn’t easy, but as Tony knew, those who are content with the status quo will always push back against new approaches and new ideas.”

Bowen’s support for a colleague may be admirable, but Bennett’s credibility is in serious question and that reflects poorly on the credibility of his grading program that Maine has copied.

When Bennett was the top education official in Indiana he instituted a similar A-F grading program for that state’s schools. When Christel House, a high-profile charter school run by a campaign donor, got a C, Bennett rewrote the rules. Under the new formula, the school got an A.

“They need to understand that anything less than an A for Christel House compromises all of our accountability work,” Bennett wrote in an email to his staff that was acquired by The Associated Press. Three days after its publication, Bennett resigned.

Bowen can blame the supporters of the status quo if he wants, but there is no question that Bennett wrote the email, changed the grade and quit his job when it became public. Bennett may be the trailblazing leader who Bowen supports, but the questions for Maine taxpayers are not as much about Bennett himself as they are about the quality of the trail that we are following.

The A-F grading system that we saw in Maine seemed superficial and closely correlated with social factors. Almost without exception, poor communities’ schools got low grades, wealthy suburbs’ schools high ones.

Now we see that the person who created the system may have manipulated the numbers in another state for political reasons. This would have been a good occasion for Bowen to defend his program and explain why that kind of thing could not have happened here. But instead he chose to throw his support — and his credibility — behind the man who has resigned under fire.

This approach does not build any confidence in Maine’s school grading system, which was already suspect. Bowen should be defending his policy, not his friend.