The court analogy is good but limited. In the USA our courts are set up to evaluate the claim of guilt not of innocence. So I think your response should be that you find God not guilty of being maximally good.
I presumed the definition of maximally good to be:
Innocent of any wrong doing whatsoever, although theoretically capability to act exists.
On that basis the court analogy would fit rather well. To show God not to be maximally good, we would have to find him guilty of a single wrong doing/crime. If we cannot find Him guilty of any wrong doing/crime, it has to be presumed that he did not commit any wrong doing/crime.
I know, based on this definition we would have to presume all non-convicted humans to be also maximally good, as no wrong doing has been proven. But as no single sane human does claim that during his/her entire conscious life he/she did not commit any wrong doing whatsoever, we can avoid that conclusion.
For God, as we can neither prove Him to be guilty of anything, nor can conclude from His own words that He commited some wrong doing, the presumption of innocence remains, as no clear evidence of wrong doing exists.
(Although i admit, i am highly curious how all that leaving a critical tree unobserved with foreknowledge of potential bad consequences, flooding, razing two cities, killing first borns, renewing an old promise of land to Israelites, while the land is currently inhabitated by other humans potentially unaware of Israelite old claims, waiting at least 1500 years before going in “full salvation mode”, etc. could be done without any wrong doing whatsoever, i realy cannot imagine how it could be achieved; but in dubio pro reo)