Why not give a similar-sized upvote on a post or comment to compensate for the downvote?
That's up to @marky, splinterlands could also just upvote a comment to prevent rewarding sniping taking half of their returns.
It is what it is, it's easy to try and find reasons to side with the person rewarding you so this comment is quite loaded. I personally think it's quite disgusting to take advantage of how the blockchain works to take rewards from a project that has carried the chain forward in many ways for your own gain, especially when they are struggling and then pretend like they didn't know any better.
If they didn't want to continue doing this they could just trail splinterlands to vote at the same time/on the same day as them so the rewards would be equally shared among them.