The steembasicincome account could simply ignore it. SBI itself has a reputation of 73 - so downvotes probably don't harm the accounts reputation if I understand the system right. And everybody only has 25% voting power for downvotes. So it would need a lot to counterbalance all the upvotes. These downvotes go somewhere against SBI anyway - either to the steembasicincome account or to accounts of members of SBI. Why not giving these downvotes some posts where the enviers of such a nice idea (and it's nothing more than that) can spend their downvotes. Anyway -they just want to harm the minnows with low SP to feel themselves great and need to demonstrate that they can stop all minnows on Steem. Most even don't post by themselves - probably they have nothing to contribute - they just fight to keep their 'position' in the SP ranking list. Why not just ignore them? 😊