A whale not voting just redistributes that unused voting influence to everyone else who is voting. The amount of money to be distributed daily has nothing to do with how many votes were given out that day nor the total SP of the accounts giving out those votes.

So whales not voting only increases inequality of reward distribution if you believe that non-whales are more likely to vote in a way that promotes inequality than the way whales would vote. Personally, I don't think the voting patterns have much of a correlation to the amount of SP the user holds. Or, if anything, I think it could even be fair to say a whale would be more willing to vote in a manner that promotes better distribution for the sake of the platform's future (and thus their investment).