If many feel strongly about "no rise", then my suggestion is strictly between the miner and the pool operator. One can choose (or create) a pool that has a zero donation policy.
it might be more valuable for a pool to scale their donations based on the price of the coin. 5% sounds well enough based on how much it will support zoidberg at the current going rate, but silly if you consider the total supply. IF we want only to help him day to day.
but as you said, pools can pick their own donation %, so the miners will decide what proportion of which % is donated!